Me and my mates at the office just bought one of those Android mk808b. Its dirt cheap, so we gave it a try.
So far its been pretty good. I plugged to an existing TV with hdmi and I can now use the TV for browsing, watching streaming videos and skype. Since I am a Linux user I got a UVC compliant webcam, which works on this device as Android uses a Linux kernel. So with little a fraction of a cost I was able to turn my old TV into what they call a smart TV (didn't like the idea of smart tv, never bought one). Normally before this TV had a laptop plugged into it, now Android stick pc replaced it.
Pros (would not elaborate on it too much, lots of people have put heaps of comments around the web)
- Low cost. These cost about $50-90 around the net. Also as part of the low cost, is that you can use your existing TV as long as it has a hdmi input.
- Small and low power. This comes with a USB adapter. However I had mine just plugged into my xbox 360 usb port, even way better.
- Newer firmware comes pre-rooted. Mine is already rooted.
Cons
- Clearly Android is for touch. I bought the bundled air mouse, you can also use normal usb mouse and keyboard. However the experience is not as nice, same experience as running the Android developer emulator on your PC. You can only use apps that will run with single touch operations or single touch swipes. Youtube, web browsers, skype, angry birds will be ok. However google maps (no pinch zoom, so I don't know how to zoom out.. zoom in can done via double tap). My idea was to get my tablet back from my kids, however this clearly an inferior experience for them. So it kinda did not work, and now they can tell me to use my stick Android and they will use the Android tablet. Plan back-fired.
- Its not well polished. This can leave a poor impression on Android for users having this as their first Android device. Though this is Jelly Bean, its really far away from the experience you have from a Nexus 4, even from a 2 year old Asus Transformer.
- It seems the cpu stays at 1 ghz no matter what the load is. Now sure why I haven't played with the governor yet. So it doesn't go 1.6ghz or drops down to 200-400mhz.
- The out display seems to be 16 bit (not sure but it looks like it), also always resets to 720p after every boots up. I read that you will need to reflash so it renders the color in 24/32 bit. Again doesn't look that good, but not too bad if don't look for image issues (gradients and dithers).
- The air mouse is sensitive to interference. I am still running on 2.4 wifi, I have not much other devices and neighbors are far away. However you can see during real big burst of traffic the air mouse is getting cut off as seen by the lag.
So the android stick PC is not really dirt cheap as it seems to be. This is probably not a good first Android device. However is a great bargain if. You have a TV that you want to run some basic computing needs (web browsing, video calls, streaming video, music playing). You can upgrade the TV and replace an aging laptop that used to perform those computing needs.
In order for the stick PC to have a great experience you need to buy a good input device. Which would now increase the cost. It also doesn't have a screen, no battery, etc. So a Nexus 7 would probably be cheaper as a first good Android device.