I don't care how well the games work—I'll buy this for the media player controls alone.
The face recognition is cool, but who leaves their Xbox on all the time? It sounds like an asthmatic dump truck. Matter of fact, the horrible racket the Xbox 360 makes when it's on is the what makes it feel less like a real set-top box solution and more like a slapdash hack.
Project Natal dev kits are just hitting the offices of developers this week, so don't expect to actually be using this until sometime well into next year.