We just bought the WII Sports and WII Fit. Too early to tell about results, but it is F-U-N! More importantly, it does not at all feel like you're exercising...until the next morning (groan).
Downside: It is definitely pricey. The core unit is $200 and the software $100. We had never done video games before and it was hard for us to get an understanding of exactly what we need to make the system work. A young man at Target gave us a 3 minute orientation, and we were good to go.
We already use a weight machine and treadmill, but this WII covers Yoga, Arobics, Strength Training, Balance Games and Training Plus (games using physical acuity). WII sports contains boxing (much more fun than you would think), bowling, golf, tennis and baseball.
It's also great for family gatherings our 5 and 11 year old granddaughters loved it; the 4 year old didn't want any part of it. The adults loved it.
Hope this helps. I'm not able to log on often, but I would be glad to answer any questions if I can. Since I am a newbie with WII Fit I'm not sure how much help I could be, but I'll try.