No problem with the gamepad besides the shit battery life, inability to turn off the screen for games where it simply clones the TV image, and that it slowly drains its battery even while it's off. All these are related to the shit battery life, and easily fixed by plugging the thing in.
Oh, the rumble sucks.
To shut off the screen, go to controller settings when you hit the home button. There's an option there to shut off the screen. It only works until you press a button though, so I'd use a different controller.