I like the idea of Microsoft's new Kinect motion-sensing technology for the Xbox 360, but feel that the technology needs to mature in order to get beyond the gimmick stage. But the first-gen devices might not make it that far.
The great guys at iFixit got their hands on a Kinect and did their usual teardown thing and uncovered what I think might be the weak link in the device - the gearing that controls the motion of the sensor head:
That seems awfully delicate to me, and I'd be very careful about even small drops of torsion to the head and those gears seem ripe for stripping.
If you're buying one, be gentle on it!