I actually worked for xbox for a little while, and the Kinect is pretty damn awesome tech wise, compared to the competitors.
The Wii isn't bad, but the Kinect sensor is pretty BA, just have to make sure you're aware of it's limitations with play space/lighting. Got a lot of calls bitching with people unable to make it work cause they either A) broke the servo motors that move it, trying to force it (bad idea...don't touch it or make the camera move by hand,) B) played in dim light, got calls from african americans and the like calling it racist, when you need really good light to play with it, it's a good sensor but it's still just tech.
I'm not sure I'd buy one personally since I don't really console game anymore, and am usually out of my house more often then I'm in it, but it's definitely fun to use. I'm sure in the next iteration of the xbox it'll be standard, as it's really something gaming consoles should have now. Wii had a good idea, but Microsoft built better tech around it.