I purchased this Android 4.4 head unit (KD-C0224) to replace an older WinCE unit. After a few weeks of use, I am very happy with the unit and have to say that it is much better than I expected.

Unit takes half a minute to boot up when you start your car, just like cold booting an Android phone. However, the video from the reverse camera (if you have one attached) appears immediately and is independent of the Android boot process.
universal 6.95 inch Android 4.4 head unit
1. Radio - Standard AM FM with RDS and presets. If your original car radio came with a diversity antenna or an antenna amplifier make sure they are accounted for in your installation or you won't get good reception.

2. DVD / CD player - I don't use this much but did test it when I received the unit to verify it worked. Played all the movies I tried without issue.

3. Wi Fi - Connects to my home WiFi without any problems when I'm parked in the garage. Can browse the web, use the Play Store to install and update apps, shop on Amazon, etc. I haven't tried the unit with a portable hotspot yet. Note this unit is NOT a phone and there is no persistent internet connection unless you use WiFi (I haven't tried the 3G USB dongle which is apparently available as an option).

4. USB input - I've put my music library on a 256Gb thumb drive and connected it to one of the two USB inputs. I use the PowerAmp app for an MP3 player, and it reads the drive and recognizes all of the 20000+ tunes available. It takes a while to read the directory (it takes a while on my PC also).

5. Backup camera - Works fine.

6. Torque (ODBII application) - I have a mini ELM327 bluetooth type unit the I plug into the ODBII socket under my steering wheel. The included Torque app displays ODBII engine diagnostic information from the vehicle computer. Supposedly some units are finicky about recognizing the ODBII adapter, mine works fine (luck?).

7. Bluetooth - Works great with my Galaxy S3. Transferred contacts phone numbers list without issue. Initiates and answers calls without issue. It also supports music streaming from the phone, but on a somewhat limited level because the MP3 tag info is not displayed on the head unit. Similarly to the WinCE unit this is replacing, you can only play, pause, and skip forward or backward. To my ears the fidelity over bluetooth in the music mode is good.

8. MicroSD Card - I've only tried it with a 32Gb card and it worked fine. There are actually two MicroSD card slots, but one is reserved for the GPS.

9. GPS - I reused the existing GPS antenna I had and it works well. Thus far I have only used the included iGo app and for basic navigation it works acceptably.

10. Front camera / DVR app - Haven't tried. I already have a separate dash cam recorder.

Take note that the height and width of the unit is a bit larger (3 or 4 mm) than the double DIN opening in the dash install kit I bought for my Camry. Some careful Dremeling solved that problem. In my case the depth was not an issue and once the front opening on the dash kit was expanded everything (lots of back connections) fit fine.

The unit looks sharp after installation and so far the screen has proven to have good driver visibility day or night. Direct sunlught will wash it out to an extent of course but it is MUCH superior to the same size screen on the older WinCE unit it replaced.

I've left the firmware in my unit unrooted and completely stock so far, but anyone really interested should check out the xda developer's forum for tons of additional info and mods.