I have just finished my first week of this. I was a little reluctant to try the yoga and even thought about skipping it, but it was by far my most difficult work out of the week. I was sweating like crazy, and was pretty much spent in the first 50 min. It is going to be difficult to complete the entire 1.5 hour workout, but I am going to try again in the next cycle.
Overall, the workouts are intense and I really enjoy it. With exception of the Kenpo at the end of each workout I have felt like my body has used all of its energy. It's a great feeling!