Just used Microsoft's Kinect for the first time last night.
It's fun and the games are almost Nintendo-ish in their hokeyness. However the fact that you don't have a controller to hold while you are doing all the strange gyrations is a bonus.
I also think that as much as some people like Wii Fit, the Kinect kicks ass based on the simple fact of its ability to give feedback on posture and such during an exercise - it busted me for not going low enough on my lunges. And with Kinect, you can't fake running by shaking the controller - get those knees up, people, or else you crawl along like a snail.
I do wish you could do more with it voice wise, though. As cool as it was to have it listen when you want to switch things around, it would be awesome if it could adjust things like volume or turn on and off by voice. I'm sure there will be some sort of update eventually that would take care of that.
So far the shine is still on the apple, so I'm sure you will eventually hear me bitching about it. But for now its a great way to keep myself and the kids active and moving on the days its too shitty to go outside. It will never replace the gym or my running shoes, but I don't want them replaced anyway.
So if you walk by my house and it looks like I'm having a seizure in front of my tv, don't worry - its just Kinect.