Hi, Kathy:
There was a time when folks around here used to use Power Max as a bench mark (no pun intended) of difficulty, but with the last few series being somewhat higher intensity, I guess it would be in a less difficult category. It builds gradually to a greater and greater intensity and impact level, which I think is hard because the more fatigued you are the more challenging the moves are. The music is slower than some, but I think that is because you spend a lot of time in the air. I also have two bad knees and a bad back, so I'm not a good one to answer this question. I hope others will join in.
I love all of Cathe's step routines. I'd be delighted if her next project were nothing but step workouts. They're all different, creative, challenging, fun, and they never get boring. If you're choreo challenged PM would be a good one because some of the choreography is relatively easy and very well broken down, while some is quite hard, so you'd gain confidence with the easier stuff that would carry you through the tougher parts. Unless you can't do impact at all, I''d get it. Sorry so long-winded....
--Ann