I just got the app and it's not bad, but could use some improvements.
Pros: Video instructions, different knowledge type (beginner, intermediate, etc) and 3 lengths of workouts. The workouts are definitely great and challenging.
Cons: Cant play Pandora in the background (haven't tried with iTunes), no idea how long each workout is as they only give it in increments of clocks (⏱, ⏱⏱, ⏱⏱⏱), the way the setup of the home screen can definitely be advanced and more user friendly.