Kinect has been working pretty flawlessly here. I only used the calibration card when I first set it up. One of the reviews I saw (the IGN one?) talked about having to calibrate it all the time but it's worked great with every game I tried since the initial setup.
Voice commands have been amazing, working 99% of the time with a normal speaking voice. One of my coolest sci-fi moments was when I had taken a break and left the Xbox at the dashboard with Kinect Sports in the drive. While on my way walking back to the TV area for another round I simply said "xbox play disc" and by the time I got settled the game was loading up. A small thing but also really freaking cool!
My only issue is my dog constantly getting in the way because he thinks I'm playing with him!
