One of my employees has one and she brought it in one friday and we all played it. She loves it, but she's a total Nintendo loyalist.
I thought it was very clunky and that the motion technology was not very realistic.
I golf a lot, and playing the golf game (not Tiger Woods, but the golf game that came with the system) was very disappointing. If you do anything resembling a real swing the ball takes off in crazy directions. The "touch" for putting was lousy as well. I found myself hitting 6 inch tap-ins 40 feet off the green. What you end up having to do is little wrist-flicks for every shot... but that's not much fun at all, and certainly not how the system is advertised.
The boxing game was a little more fun, but still less fun than a standard boxing game on a regular system.
The tennis game was ok, but that's only because I dominated the whole office at it.
All in all, I found the whole thing to be gimmicky.