Okay, back.
Didn't get to play for long, but here are my impressions.
They let me play the ball game and almost the river rafting game. I tried to get the guy to hold my iPhone and film me and he just kinda said "No, we were actually specifically told not to do that."
Okay, so, load up the game and it shows a picture of me and asks me to stand in the silhouette so it can sync. Not a problem. I do and....nothing. The guy looks at me, I look at him, and he says "Oh...your shirt is kind of dark."
Which, well, it's not. So after some finagling and me going out to my car to grab a bright red hoodie I have in there, it finally worked. So I start the ball game.
For the first minute or so, it really is minority report but real. It does not feel nearly as floaty as I assumed it would and at times I was getting the kind of precision I'd expect from a Wiimote pointer or even a mouse. Then that kind of goes to hell once you, you know, move. The ball game seemed to only see me on a 2D plane, so the second I stepped forward to hit a ball (dodgeball strategies rushing back!), the game assumed I got way taller for no reason. When I stepped back, my legs desynced and they were literally floating above the ground.
The guy tried to shift me back to the ideal position, at which point Kinect fixed itself, but for the life of me I saw nothing that would indicate what that position was, save for a black piece of tape on the floor.
I couldn't tell if it was sensing depth or not. I didn't see a difference in velocity or angle when I'd try to, say, punch a ball down. It just bounced off my fist like I force pushed it back.
So that was oddly tiring. I wanted to start up the river demo, but the guy said it was time to pack up and it's only really fun with two people, so it would be a waste of my time. I told him fair enough and came back.
So my overall impressions: If they can repeat that moment of "Wow, this is cool" throughout a gameplay experience, then it will probably be a worthwhile idea. If not, and that is an immensely tall order, then they might have gotten the technology ready without really being prepared to do something with it.