If you know what youre doing and know the required posture its a prettx good app. If you are new to suspension training read a book or participate in some lessons at a gym.
Concerning what i use the app for its all that is neccessary. Workout creation is good. There are quite a number of different excercises. In my opinion there is not enough time between the excercises in a tabata workout to come from an upright-standing-position into push up position with the feet into slings. You can avoid the problem if you configure your own workout, though.
If they dont charge ,me twice cause i installed this on the phone AND on the pad, the 4 stars are well earned. At least to me.