The game is divided into four areas: balance, yoga, aerobics, and strength training. I think the game is perfect for me. I never work out so I'm a little out of shape. The exercises are tough enough for me but if you are the gym going type who runs like 12 miles a day, leave this game on the shelf for the rest of us out of shape Americans :) The one thing and probably only thing I don't like about Fit is that there is no flow to the game. You can't select multiple exercises and set up a routine which would be even more perfect. You have to select each separate exercise you want to do which means there's a bit of lag time between each exercise. Not a major problem but still something I noticed.
Each minute of exercise you do goes into the Wii Fit bank which unlocks different games after you collect a certain amount. I haven't unlocked most of the games yet but I'm looking forward to it! So far my favorite is the hula hoop and the strength training. I can really feel the strength training working my muscles. I used to take yoga classes so that was one of the reasons I really liked Fit. I have yet to try much of the yoga though since our living room is a little tight.
Pics from http://e3nin.nintendo.com/wii_fit.html