i assume you're talking about yourself fitness. i have it. i've been doing it for a few weeks now. i like it, but it could be a lot better. i'm excited about the next generation of this game because it's such a good idea. as you progress, maya (the personal trainer) gives you tests and you get access to new songs and scenery, and for some reason this is enough to motivate me. she also asks you if the workout was too easy or too hard and then makes changes for next time.
my main problems are (1) the music is lame--but i guess that's the case with any workout video, (2) I hate some of the exercises but can't get her to stop doing them (ie, there is a lame slow kick move that she always does, and this "hustle up and back!" thing that i hate), and (3) i think you're expected to have a step, ball, and hand weights, because without them some of the exercises are off.