I truly believe that if anyone is grumbling about the tracks not being intense enough, it's because their technique is lacking! With all the alternatives and options of using weights, I don't see what they are complaining about.
I like the fact that the exercises change every release -- which I think is great for challenging the ab muscles.
I personally like taking a BodyPump class followed by a Body Balance class -- so that I get two ab workouts!
... so that's my 2 cents.
"Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body, but rather to skid in sideways, chocolate in one hand, wine in the other, body thoroughly used up, totally worn out and screaming 'WOO HOO what a ride!' (Author Unknow)