I'm a Mii (that's Wii Hua for a Wii owner).
I like the realism of using a wireless control and performing virtually (eg. you actually swing the remote as a racket, bat, golf club in those games). I picked up a 5 RMB copy of Guitar Hero 3 recently and am on the lookout for a Wii Guitar - actually a guitar shaped piece of plastic that the Wii remote snaps into so you can play air guitar along with the groups in the game.
I realize the graphics aren't as sharp and realistic as in the X-Box or PS3, but the sense of action is much more realistic. And it's good exercise, especially the boxing game that comes with. I also believe it can hone your real life skills. I got my Wii last spring. I play Tiger Woods golf about 3 times a week - actually standing there and hitting like the real thing. Chipping and putting, too. This summer and fall I played (real) golf 4 times and shot mid to low 90s - haven't broken 100 in 10 years.
Another benefit, one I mentioned in an earlier post - the console is tiny, about 2/3 the size of a cigar box and setup is fast. I bought a small Wii bag that everything packs into in less than a minute so you can carry it around wih you - take it to a party, to the local bar, to your classroom (if it has a TV), traveling...
Cost-wise, I got mine (Japanese version) for 2000. The bag set me back another 50. I also bought a "Sports Pack" for about 80 which includes about 6 or 7 different plastic pieces that the Wii remote snaps into so it feels more realistic (eg. baseball bat, tennis racket, steering wheel). I've also seen Wii rifles (a plastic rifle the Wii snaps into) if you like the shoot-em-ups.
There's a new Wii Fit board out now that you stand on. You can do yoga, balance exercises, be a football goalie, surf (the water type), ski, etc. standing on it. It's 8-900 RMB at the mo' so I think I'll continue working on my putting and hitting behind the runner.
If you do test out a Wii, don't just use the cartoony Sports Games disk which comes with it. Check it out with a couple of real games like Tiger Woods, Need for Speed, Call of Duty, as well.
Well, that's my take as a Wii fanboy.