While not as enjoyable or polished as Wii Fit Plus, this is worth getting as an alternative.
The resistance band, while not very powerful, is certainly a better method than trying to treat the Wii Remote as a dumbbell. Plus, once you get the leg strap on tight enough, it certainly allows the game to follow your lunges and squats.
Essentially, this is a more interactive version of Fitness Coach; with the idea very much to stick to an exercise regimen, rather than dip in when the mood takes you. A fair amount of effort has gone into explaining and demonstrating the exercises, although I would say that either the female trainer is a midget, or she has a much longer nunchuck wire; as I found that mine became fully taut before I'd completed some of the moves properly.