I've tried it more than once in Best Buy and I can't make up my mind if it's a gimmick or sheer genius. I feel like an idiot standing there flailing my limbs.
I'll be keeping my controller and kinect at the same time. It depends on the game that you play. I play Halo, COD, Far Cry and I have already developed my quick reflexes and accuracy using a controller, . While platform games like tennis are best played through kinect.