I definitely see vertical lines artifacts in 2160p / 10bit videos in the testing1 build.
Also, there is some weird macroblocking and flickering, for instance in the Samsung Wonderland demo in some of the skies - look for the top middle of the screen. Those artifacts are gone when I use the TV internal media player.
I think 1080p content is fine.
My AVR does not like 4:2:2...
Well, it would have been for testing only. In the end I need to think about another solution to get HD audio to the AVR.
The vertical lines have been in all 10bit output I've had on s905x (android and LE), so I'm not sure what can be done about them. However, I don't notice them at normal viewing distances. I just ordered a s912 box, and will see if they're also on it.
The artifacts I'm not sure of, but they could be related to chroma sampling. I'll work on manual 4:2:0 and see if they're still there.
Edit: you could try a 25, 30, or 60fps video to see if they're still there.