Now it's out and NDA has terminated...
It's brilliant!! Had mine since 31st August
First few weeks I thought it was utter tosh, VERY temperamental, the games were slow and laggie and trying to just get it to recognize movement was abysmal (the voice recognition worked flawlessly though).
Throughout September, updates to the software and firmware were a regular occurrence, and as time went on things started to improve dramatically.
We've had to perform a shed load of tests; wearing bright/dark clothes, clothes that match the background of the wall, having people jump in front of the controller, moving fast, all sorts and it's worked flawlessly.
First few weeks there was lag, as of the last update at the end of October I've experience NO lag at all PROVIDING it's calibrated properly (you'll receive a little card with a face on it that you position at various distances, I strongly advise you to get this working to perfection for ultimate experience).
Hardware wise it's rock solid, it feels a damn good piece of kit. The motor is quiet, the cable long.
For anyone with the non-slim XBox360's - you'll need a spare power outlet. Those with the new slim ones, it just plugs into the back.
Only thing that is a pain is selecting something/clicking. You need to keep you hand still over an icon, hold it there for a few seconds while a 'spinner' icon goes around and that activates the click.
Overall, impressive, VERY impressive.
How it will compare to a Wii - hardware wise I think it's better but as I've said for years - it's the software that powers the hardware, yet again the software industry is armed with a great piece of hardware, let's hope and pray they don't ruin it.
YES you do need some space, but you do NOT need a huge amount of space. I've tested it in a small bedroom and providing it can see the floor and has about 6-8 foot of space behind you, you'll be fine. But, bigger is better, especially for MP action.
Games:
Kinect Adventure - I personally enjoy it, good fun.
Kinect Sports - It's incredible fun, but not really my cup of tea.
Joyride - LOVE IT!!! Great fun and definately can't way to have some MP action with this.