I have just purchased this having owned the wii fit since last May. I feel it is far better then the Wii fit, the workouts are tailored to your fitness level and needs. It starts off with a fitness evaluation measuring yourself and your heart rate this then assists the fitness coach to assess your needs. The workouts can be from as little as 15 mins upwards so if you are struggling for time you can always fit in a quick workout. It suggests which areas you should work on and after 10 workouts it then looks at your progress. I found the wii fit boring after a while the trainers say the same quotes each time, this is upbeat and far more motivational.
I would highly recommend for the price. You can also incorporate a step board, weights, ball and heart monitor into your workouts if you own them.