I get my large (but shrinking) a## out of bed at 4AM every morning to do Turbo Jam. I also have a ton of other DVDs, a bike, treadmill, eliptical and bowflex and I can honestly say that turbojam is the only thing that I will consistantly do. I have been doing it at 4AM for about 2 months now. It is fun, the music is great and the instructor has a fun personality. It also doesn't involve any complex things like steps, etc. I enjoyed series 1 so much that I ordered series 3 and am looking to get 2.
For me it is definately worth the money.
Good luck!