Get Fit with Mel B is an excellent alternative to the other workout games on the market. Although, I feel Get Fit is tilted more towards the already fit, it will get you in shape. Mel B is a workout machine and watching yourself beside her incredible physique can be both discouraging and empowering.
If you want to do something for your personal fitness level, Mel B can help you a lot. One problem occurring is that PlayStation Move is easily tricked, hence you're led to cheat. Maybe Kinect can do better?
This game won't get you to the summer olympics, but it's a good first start toward a healthier lifestyle.
Much more enjoyable with Kinect, Get Fit with Mel B is a fairly good fitness game, lacking some original exercises and online options.