i've had the biggest loser wii game for a few months now and i really, really like it. actually my favorite of all the wii fitness games; it's got the biggest range of difficulty, and provides actual resistance work. there are a few exercises that don't register well (such as woodchops) which i initially found frustrating, but i've let go of my need to get 5 stars on each exercise and just make sure i work hard.
it's a better workout than my fitness coach and less repetitive than ea sports active (the first one, for sure. i like the second one better but have found myself moving away from it because the voice-over lady is so friggin' annoying.)
highly recommend. wish there was more dedicated cardio and the music doesn't do much for me, but it's the best from what i've tried.