I just did a review of Xbox 360 Kinect, and explained why Microsoft got it right this time and gave every holiday game shopping something to cheer for.
For details, you can visit here.
The bottomline is that Kinect is far more advanced than Wii and PS3 Move, and its unique capabilities make playing games fun much more fun too!
I got my Kinect bundle at Amazon for $150, but such great deals are not always available. My advice is to get one right now for the X'mas time, so you can avoid paying a higher price later, remember the shortage of Wii controller a few years ago at X'mas time and its subsequent price run?