I have a Wii myself in addition to my 360, and I actually do enjoy the motion controls when done right, unlike most. One of the big problems is a lack of resistance though. For example, in the Wii Sports Resort swordfighting game, you swing the remote as an onscreen hit, mapped 1:1 with the game. But when you hit the other person's sword, there's nothing in real life that stops your momentum, which can make things feel awkward. That's bad enough with a controller in your hand, but I couldn't imagine how awkward it would feel if not only that, but I wasn't actually swinging anything.
Same goes for driving. The Wii wheel, since it's not attached to a central axis, gets enough crap on its own (rightfully so in my opinion, I definitely don't use the plastic shell for that), but isn't just twisting your hands around in the air going to feel worse?
I don't know, I guess we'll see. The technology is definitely interesting, but I have a feeling for games with motion control, I'll be sticking to my Wii, and for the more advanced games I'll be sticking to my 360.