I had some issues with the game, but anywhere near the ones you having.
The sensor sometimes mess up my moves, like when I stretching my arms straight ahead to go for the hud vision and the sensor understood I was raising my arm and put me in to the periscope vision, or turned on the high speed mode.
But the real challenge for me is to change ammo, no matter what I do, I can rarely put up de HEAT round. The sensor just donīt understand it.
It is a fun game and all, put aside the really high dificulty, but I think Kinect doesnīt like me, no matter how much I want to like him...