This is the stock Rikomagic USA RK3066 Dual Core firmware running Jelly Bean 4.2.2. It seems very stable, but you need a very good wireless connection.
Some routers with old firmware might need updating to be able establish a wireless session. SD video playback is very good, but 720/1080p might be too slow and audio sync and pausing issues.
Some Google Play Apps show up as not being compatible (due to the device not being recognized as a generic Samsung phone), but most games and Apps run. Netflix should run as well as Hulu.