All explained in the title.
It affects the players view in first person (the hand on bottom right of screen), in third person view and in other player's view on multiplayer.
I don't know wether it's only for doors or all half-blocks.

Note: I wrote iPad Air 2, but my bro and my friend were on an iPad 3 each, and the same thing happened. (they both had IOS 8.3, though.)