I have mixed feelings about this game. I've only played it a few times.
Pros:
* The exercises are more challenging than the Wii Fit ones, i.e. I can work up a sweat.
* The challenges are fun.
* Having the trainers we love from the TV show is cool.
* The best feature is probably the custom routines. You can pick and choose exercises to create a routine - and it tells you how many minutes of activities you've chosen.
Cons:
* Once you choose an exercise - even a 30 minute circuit training routing, there is no way to exit or back out without just shutting off the whole Wii. This wouldn't be such a problem, except I found the menu a little twitchy and my Wii-mote would select something I didn't mean to pick.
* I got kind of bored during the circuit training workouts. There are 5-10 seconds of waiting between each exercise. It feels like you're just doing a workout video, but not as interesting.
* While the challenges are fun, there is a very specific way to do the moves - I've been frustrated that it doesn't recognize my movement about half the time.
* The scoring or telling you how well you did seems arbitrary
* There is no cumulative calorie count or summary screen for your total workout. You'll just see the calories burned for the last activity you did. I was bummed that I did a challenge, then a circuit and didn't know how many cals that was.
* The trainers have a set number of phrases, and they are in a random rotation. This is fine in theory, until you're doing a relaxing cool down and Bob yells out, "Keep pushing through it - don't stop!"
* The weigh ins don't match with what the game does. You don't play as yourself, you pick a character from a former season. Your actual weight is not commented on. Your character gets on the scale and is weighed. How the character does is all that you see. For example, I lost 2 pounds, which is good for someone my size. Well my contestant Michelle only lost 1 and ended up below the yellow line.
I was really excited initially to get this game. I think I will continue to use it, but only rarely. But other people seem to like it a little more than I do. I think if you're expecting an interactive workout video with a few elements from the BL TV show thrown in, you will like this game.