Two gents in my residence hall camped for the Wii.
The first thing that struck me was the size of the thing. I'd heard no reports, and was pretty much expecting a vertical N64, but it's not much larger than a VHS cassette.
I played Wii Sports with a group for a while. The controller is very smooth, but it does require some distance between the user and the sensor bar to work well. The bar is a little plastic strip with sensors that apparently triangulate on the controllers. Offhand, it's about 1cm deep, 0.5cm tall, and 10cm long - just right for sticking on top of a TV.
The controller is remarkably intuitive. The two owners were using them like pros inside ten minutes of picking them up, and the feel of them is extremely good. I have colossal hands, and the reviewers are pretty average, but we both thought the fit of the controllers and tactile response of the buttons was superb. According to the users, the motion is precise, and quickly becomes intuitive. One commented that it was great to get motion back into games. Immediately after playing with the Wii for a little while, I went back to another room ans used a Gamecube. That's when it really hit me what a revolution the Wii's controller is.
Asus A8N32-SLI - AMD X2 4200+ @ 2.7GHz - 2 x 1GB Corsair PC-3500LL @ 266MHz, 3-3-3-6 - SLI 7800GTs @ 505/1206 - Corsair HX620 PSU - Cooler Master RC-690
The two great evils of system tuning: YMMV and IIRC.