Pleasantly surprised :)
While this game does utilize the Balance Board it is only specified for certain workouts. These would be the more physical workouts like squats, sit ups, and so on.
Where the real workout/cardio takes place is with the WiiMotes in the boxing exercises. The great thing about this is you can use two Wiimotes instead of a Wiimote and a Nunchuck, so you don't have the wire getting tangled while boxing. The boxing, which still gave me a workout on Wii Fit and even on Wii Sports is way more active and is basically the focus on this game. The more difficult boxing exercises range from 15-25 minute workouts which really get you sweating.
It's very easy to find your way around the game, and to follow the workouts with your trainer. An added bonus (in my opinion) is you can even pick a song to do your routine with so you don't get bored with the same rhythmic tune.
I thought this game would be another corny workout game but this is exactly what you expect out of a cardio workout. Even when I saw routines like jump roping and running I thought those would be tedious and not enjoyable, but I was wrong when I tried it out. It's much more enjoyable than the activities on Wii Fit and Jillian's Ultimatum. The controls are great and I love how this game just gets your heart pumping!
Even if you don't have the Wii Balance board, this game works great and you won't be losing much in the end. If you're looking for a great workout game, pick up this game for $30. You won't be disappointed.