It’s fun!
It’s tiring!
Most of the games probably aren’t so hot for long-term play, but they’re great for jumping into and just having a bit of fun for a not-so-long time, especially sports. Boxing is a little weird, but the others are as you expect (Golf is probably my favorite).
I still don’t have one; a guy at work brought his Wii into the office with about 4 other games and we’ve been playing with it a bit this morning.
In terms of technology it seems more like a toy than a “Next Gen” system, but that doesn’t mean that its not fun. I think Nintendo did right by going in this direction, especially given that Sony has the technical edge (and 360 isn’t so shabby either)