Personally, I don't think the skirts thing should be an insurmountable problem, however I don't doubt it's not a trivial one. If you can see the feet, and it records your height, it should be able to guess when you're up straight. If the skirt width (assuming there's good enough contrast to make that out) isn't changing but height is, chances are you're kneeling/bending over. If the skirt gets wider, or the foot moves if able to track, then there should be useable data. Won't be 100% accurate as seeing joints, but might be good enough so people don't notice when playing most games.
It does sound like they've done the minimum to assure a releasable product, and not a great amount in the "innovation" department. I don't have a 360, so won't be getting it, and it doesn't really make me want to get one either. I have a PS2 eyetoy and a Wii. Eyetoy I did use for gimmicky games, and that's all I expected out of it. I think it's going to be a hard sell at that price, especially if the only good games for it are on the casual/gimmick side of things.