Harley Pasternak's Hollywood Workout is the second workout game I purchased for the Kinect. I found it to be an enjoyable, if repetitive experience, much like any good workout program in a non-electronic world. The cardio warmup and cool downs properly made my heart race, while the 5-week program switched things up on a day-to-day basis to keep things interesting.
The fact that one of the achievements required a minimum of 10 weeks of activity and another 5 weeks kept me engaged in the workouts.
None of the achievements were particularly difficult to complete so long as one remained engaged in the workouts.
If one is looking for a quick completion, this is not it; however, for an engaging workout routine, I believe one could do worse than Harley Pasternak's Hollywood Workout. One is required to maintain 15 weeks of regular workouts before completion. This effectively exploited my desire to complete games while simultaneously forcing me into physical activity. That sounds way more sarcastic than it unfortunately is for me; tricking myself into healthful activities is a regular pastime for me as I enter my 30's.