I have an ipac 2 and a Pi b. I have had great success on getting this working for the most part.
There are three main issues I am struggling with.
1) SNES Emulator does not recognize player 2 controls, even after I tab into set up the controls. 2) NES Quit/Esc button does not recognize and I have to force shutdown the Pi to reboot to PiPlay main menu 3) My Happ 3 button track ball is not recognized. I can roll the ball and it takes me into code mode, which is annoying.