I downloaded the new Minecraft PE 0.12.1 onto my iPad Air 2 running iOS 8. I am using a Mad Catz C.T.R.L i controller that I bought to play Minecraft on the iPad. Everything connects and works pretty well. One major issue I found with controller support is that when I use the two joysticks at the same time to move forward AND turn at the same time (a feature that typically works really well on a controller) the movement on the screen is really jittery. It's almost like the game or iPad can only understand the movement from one joystick or the other, but not both at the same time. I can use each joystick independently and everything is smooth, but when I try to use both to move forward and turn at the same time it gets really jittery.

In this youtube video that I recorded (https://www.youtube.com/watch?v=wLt-PAXhC8k) you can see I fly up, move forward, back, left, right and turn with out any jitteriness, but when I try to move forward and turn at the same time it begins to jitter/stutter.