I purchased this June 15th, installed it June 17th, and decided to wait until now (July 29th) so that I could give an accurate and comprehensive account of my experience. I was hesitant to buy it at first, just based off of some of the other reviews, but now I realize that their problems may have been caused by improper installation of the unit (improperly connected wires would burn out even a Pioneer). I recommend carefully reading the installation instructions once or twice before starting, and also buying a new wiring harness for your particular vehicle that includes a color code guide. I also strongly encourage you to disconnect the battery before even messing with the wiring or plugging in the unit, otherwise you cause damage to it. Now for my experience using it... I really honestly love it. I looked around for a long time trying to find something that was reasonable in cost, but still provided me with all the conveniences of a significantly more expensive (400-700$) unit like a Pioneer, Kenwood, or even JVC. In order to make my review more readable, here's a break down of things that I felt were important. Also, I completed the install on my 2002 Dodge Ram 1500 Quad Cab, using the Metra 95-6522B Double DIN kit.

SOUND QUALITY: The built in equalizer is not amazing, BUT, if you have an app like Spotify you can set the stereo equalizer to Natural or Flat and then turn on the equalizer in Spotify, and the sound is beautiful. As soon as my wife showed me that I could do that, the difference was like night and day. I should also add that I installed a brand new set of Boss speakers in my truck, but no sub-woofer setup.

DISPLAY/TOUCHSCREEN QUALITY: Significantly better than the touchscreen stereo I previously had in my truck. It's basically like having an Android tablet built in to the stereo. When using Google Maps, the text is clear and sharp. I can even read my email, or a pdf document comfortably. The touchscreen is very responsive, and doesn't require an excessive amount of pressure.

VIDEO QUALITY: I frequently use this to watch YouTube, or Hulu during my lunch breaks, and as before it's just like watching it on a small laptop or tablet screen.

GPS ACCURACY: The GPS antenna is great, accurate, and there's almost no lag in position update. What my wife and I will typically do is turn on the mobile hot spot in our phones so that we can connect the stereo to internet, and then use Google Maps to load the directions and start the navigation. I've done this many times for long trips, and it's worked out great every time. Even without an internet connection, you can still use the map and GPS to navigate yourself, which is something we've also done once or twice while stuck out in the woods.

WI-FI CONNECTION: I can easily pickup the Wi-Fi signal sitting in the driveway near our home, and download updates, etc... Though usually I just turn the hot spot in my phone, and the connection is fast and reliable.

BLUETOOTH CONNECTION: I've never had an issue with this unit and connecting to my Android phone or my wife's iPhone, it's easy to setup and modify connections, and connects immediately. I previously had issues with with my old stereo and the Bluetooth connection randomly dropping/disconnecting and then reconnecting, but I haven't had any problems with this one.

OTHER: So there are other attachments you can buy to use with this stereo. A Backup Camera, Front Facing Camera, OBDII Bluetooth Reader, and in my case an Amplified Data Interface to keep the stereo on until you open the cab doors. Eventually I would like to install all of these things.

CUSTOMER SERVICE: They have great customer service, I got a full response within 24-48 hrs, and they even took the time to send me links to additional components that I might need for my particular install. I'm not sure why they've gotten some poor reviews for their customer service or helpfulness, they honestly do seem to care about doing whatever they can to help you.

OVERALL RECOMMENDATION: Having used this unit heavily over the last month and a half, I can say that I wholeheartedly recommend buying this unit. If you've got a used or older vehicle that you love, but don't really want to put a 700$ stereo in it, but still want to have all the features of a newer stereo, this unit is perfect for you. I'm very happy with my purchase, and if this unit ever died on me in the future, I would still come back and buy another one. Also, this stereo WILL fit with the Metra Dash kit for the 2002-2005 Dodge Ram 1500s, you'll just have to cut out some more plastic on the inside of the dash so the unit slides all the way back properly.

UPDATED REVIEW 9/3/2018....

Working with ATOTO engineers to resolve issues previously listed. So far customer service is very responsive, even on weekends. There are still some minor issues but, I think some of the issues will be solved with a software update which ATOTO is known for producing often.

Really great system. Huge improvement over the M4 series. I have a 2011 Subaru Outback, bought the metra 2DIN faceplate and wiring harness. If you go to the Crutchfield website and enter your car they have a feature that tells you all the parts you need to add an aftermarket head unit. I bought all of the connection parts there. I installed both the units myself with no previous experience installing a head unit. Took a whole weekend and a lot of self-guided instruction but worked perfectly both times. The reason I chose ATOTO to begin with is the 2 sec. load feature. It's really great to turn the engine on, program the map right away and then hit the road. Waiting 30 sec. or so for a boot would be frustrating.

Biggest problems with the previous M4 and improvements in the A6:

M4: Microphone was terrible bordering on unusable.
A6: Microphone is loud and clear. My wife told me she had to turn the volume on her phone down because the microphone was so loud. No more screaming into the microphone!

M4: No bluetooth tethering. Wi-fi tethering worked but dropped frequently and awkward to connect.
A6: Bluetooth tethering works very well. Big problem with the tethering system in general is that Android no longer allows turning tethering on and off via a macro so it has to be done manually. I added a shortcut to the A6 screen that links to the Bluetooth2 settings so that I can easily turn tethering on even if I forget to do it on my handset when I first start the car. Apparently, Android 8.0 will allow automation of this feature again, can't wait.

M4: Frequent crashes. Really slow to load large apps like google maps.
A6: I bought the model with more RAM and it is a huge improvement. For the extra money it is well worth it. Much more responsive and stable.

M4: No physical buttons!!! Basically unusable unless you get steering wheel controls working, even then feels limited.
A6: Probably the best improvement. It is dangerous to only have touch buttons while you're driving because you have to take your eyes off the road to press them. The physical button layout is not how I would have done it but it feels so much safer to be able to make changes without looking away.

I have the discontinued ATOTO backup camera as well. I had it installed at Best Buy because I didn't want to take apart the whole car to install it. Cost $100 to install, money well spent. Camera works great. High enough resolution you can read license plates with it. Many other stock backup cams I've seen are very poor resolution.

Support is responsive but located in China so responses are usually delayed 12-24 hours. All of my support questions are always answered very thoroughly and generally don't require follow up questions. No noticeable English issues when receiving support. They are open to suggestions as well and several of the things I suggested for the M4 have made it into the A6.

The pictures are of the unit in place in the Outback. Looks like it belongs. The buttons below are from the stock Subaru bluetooth unit that I disconnected. I still haven't figured out how to wire those buttons into the A6 but it would be awesome if Subaru would give me the wiring diagram for it.

Cons: no android auto since it is technically a tablet so the system will not read your texts, alert you to texts, etc. Not a major loss but would be a good feature.

Installed but have some issue with GPS. While is navigating , it shut off by itself while the radio keeps running. The app ( google Maps ) close by itself and the unit goes back to the home. Installed a different offline GPS App but didn't try it yet. Will update next few days.
UPDATE May 9th. The best app to install is Tom tom GPS. It works perfectly and the radio handle it without issue. In this way no Internet required. So far is a good radio.
UPDATE May 11th. Radio works great. Customer service provided a solution for Google Maps. Everything works great. Now I have two GPS app installed and I can select whatever I like.

Item: PRO A6Y2721PRB-G

Pros:
Fits American Double Din standard openings (and trim pieces). This unit is smaller than the other Android OS based head units and fits perfectly with what I had understood to be normal Double Din openings (I now know there is a European standard size and an American size) like pioneer and kenwood units
The pro version has an upgraded screen and I have to say it is totally worth it, it's so much easier to see during the day.
Steering wheel controls work well
Back up camera works well
Bluetooth works well
Wifi performance is good (noticed some comments about 500k speed i'm getting 30MB+ in my garage)
The sound is good

Cons:
The screen protectors are worthless DO NOT INSTALL. Tons of bubbles and unlike other screen protectors where you can slowly work the bubbles to the side to get rid of them this one has real adhesive that smears and won't let the bubbles move completely
The steering wheel controls only do a single press, so press and hold is the same as a quick press
The gestures often get confused when you are trying to use the keyboard on the screen and open the music app
I don't like the screen being inset, it would be nice if it was flush with the trim

I've only had this for a few weeks (at the time of this review) so I can't give a long term usage review yet but so far I have been really pleased. The screen on the Pro version is definitely worth the extra money. I have used this in pretty bright sun and still been able to see the screen well. As I mentioned above DO NOT install the screen protector. I spent a fair amount of time trying to work the bubbles out and had to give up, the adhesive is too sticky and won't let you move the bubbles around well (on mine it left smeary looking bumps). It was also really hard to get the screen protector back off due to the screen being inset into the trim.

If you are looking for a completely flawless experience then you should probably not go with one of these android OS units. But if you are willing to deal with a few issues and quirks (for instance if you push "pause" on the FM player and then turn off the car the stereo will be playing when you turn the car back on) in order to get a more tablet like experience on your car stereo then this should work.

I purchased 2 ATOTO A6 Double DIN Android head units in early April, 2018 to replace an older Pioneer head unit in a 1998 Nissan Sentra B14 and a BOSS SINGLE DIN 2000 MAZDA Protege.

In both instances the installation was not difficult. It was a direct fit for the Nissan and surprisingly easy with the Mazda after market installation kit which was acquired from a local electronics shop prior to installation.

The Nissan has four speakers and a powered low profile 8" SUB by BOSS while the Mazda only has 4 speakers. In both cases there was an immediate improvement in the overall sound in both cars with the unit set to flat. There is an unmistakable warmth in both machines with much less listener fatigue with the any of the sources used (FM radio, MP3 and other formats).

The sub woofer is now much punchier on popular music such as Jazz, R&B, RAP, and deeper on Chamber and Organ music to mention a few. It would have been great if ATOTO could give more flexibility to the SUBWOOFER control software.

Give a more detailed filter system such as Low and high pass filters with adjustable slopes. At the moment I have to make adjustments when I switch from one type of music to the other while driving. Thanks to the IR steering wheel controller, which is a must, you can quickly adjust the volume level. A source level adjustment may be useful.

My likes : Sound, handsfree calling (beginning to prefer Android Auto although the latest update makes for easy connection with their Easy Connection App), WIFI, BLUETOOTH connectivity and the ability to tether all go together to make updates and customization much more pleasant. The reverse camera works well. I have not tried the dash camera yet.
AFTER SALE SERVICE EXCELLENCE. The service is a great experience and refreshing. One of my SWC wireless controllers did not work. I signed up, registered the product and emailed them. Sure enough there was a response and expert help provided. With no hesitation a new one is on it's way.
Don't like:
The need to make major adjustments when the sources change often going into the SUBWOOFER menu after quickly rushing for the vol + or -.

I would recommend this product to anyone looking for a clear powerful sound at a reasonable price. The after sale service has so far been outstanding.

Just finished installing A6Y2721PRB in my Solara JBL 2006 w/ the dreaded JBL Amplifier. Honestly one of the cleanest installs I've done in a while. Also I needed to do this urgently as my radio crapped out and I was driving around without any controls in Los Angeles traffic. I used a harness kit so I wouldn't have to tap into the factory wires and from there every connection from the harness to the gps/camera/wifi/mic/etc you name it, was super easy

Pros
- Incredibly fast. When they say 2s boot up time ,they man it.
- It's a beatufiul headunit. Polished packaging and device you really feel confident it'll last. Everything was considered when designing this unit.
- Double Din fit is on point. I recommend getting the headunit first and then seeing how it fits in the car before needing anything else (unless you dont have a double din already.)
- No issues at all with visibility at night or in the day
- I might be over excited but the camera looks better on this headunit
- Hotspot internet from my phone to the device and it's as if the unit has internet seamless

Cons
- Not many really. At this point there might be 5% that might be good or bad but that's always related to Android experience
- Customization is there but i wish it was easier. I have spoken with support and they are looking to add something in the future
- Honestly I'm glad the unit doesn't need it but the Screen Protector could be better if you did install

One of the major gripes I have with units is install. That's 50% of it and needing this installed quickly I was super happy that the install was smooooth. Can i add more o's lol. The upgrade is worth it knowing that the unit will last and be current with all the features that you can want out of a unit. Everything on the unit is crystal clear and being able to use 2 devices on bluetooth means thats i wont have to keep disconnecting and reconnecting based on whichever device connects.

Install was easy. Did not include a separate microphone input for speaker phone, however the mic in the face works very well.
Using it for the past week, I'd say it's better than advertised. Integration with my iPhone has been seamless. I can either turn on hotspot, and use for navigation, or just stream BT audio straight from my phone. Calls are hands free and very clear. Running torque with a BT adapter is great, as I now have an eye on parameters of my vehicle I didn't before.

I will say that the volume buttons "seem" backwards to me. As the left button turns up, and the right one turns down. But that's not a show stopper.

All and all if you are looking at carjoying, pumpkin, or this. I'd recommend this hands down.

Installed in my 03 F150 with not much fan fare. Not my first head unit install, and this one went as smooth as I could have hoped. Audio quality was SURPRISING! I did not expect it to sound this good. In fact, due to the factory sound, I never got around to installing my Polk 4 channel amp. Though I will move forward with that this summer. It sounds far better than my factory 2016 WRX radio. Mind you I am currently running polk 2-way 5x7's in the front and factory ford speakers in the rear.
Boots very quick, though it seems like the wifi card or memory is a bit slow. It takes a VERY long time to download my music on wifi despite being connected to an ASUS gaming router and a 1Gb/s internet connection.
Blue tooth is clear, and i did not get to install the factory Mic, so I am only using the front one. My exhaust is a bit loud so people do say they have to turn up their bluetooth to hear me better, but I am clear enough.
GPS works, if its up to date. Remember to connect it and download your local maps (using google maps).
The amazon music app is just as buggy as it is on your phone. Cant blame the head unit for Amazon's inability to make a proper app capable of offline music.
Equalizer sounded best on "classical". You can use after market apps.
Bluetooth one is controlled through the phone icon. Bluetooth 2 through the android drop down menu. Takes a little getting use to. Radio reception is actually better than the Pioneer Navi unit it was replacing, but that unit was 8 years old.
If Atoto made the factory fit replacement unit for my 16 WRX i wouldn't hesitate to buy it. In fact I have recommend this unit to other people because for sub $250, it cant be beat at this time.

I plan on installing a backup camera when I install my subs and amps this spring.

If you're in the market to purchase a new car stereo, and you're an Android person, this is the one for you. I had a JVC for years and it recently died, so I was looking for it's replacement. I spent hours researching all the new features and different manufacturers. When I found the Atoto A6, my search was over. This is exactly what I was looking for. It has 3 USB ports that you can use for flash drives and charging phones. Also has a micro SD slot for additional storage. Everything else is like using a Android tablet. Any app you can get from the Play Store, you can install on this. The radio comes with a WIFI and GPS antenna. The Waze app works very well (even offline). I also puchased the dash cam, connected via USB and works great, so far. I had some trouble getting the steering wheel controls to work, but support was very responsive and we got them working. I have a 2013 Jeep Wrangler so if you're on the fence, make the purchase, you won't regret it.