RE: Interval Max!
It's not good - it's GREAT!
It's a step routine with an extended warm up on the step followed by 10 intervals (1 minute aerobic step work, 1 minute aerobic-to-anaerobic step or floor-jump work to push you to your cardiovascular limit, and 1 minute recovery per interval).
Basic choreography (in fact, if you're new to Cathe it's a good workout to learn some of her core choreography as well as blast you off!) and ultra-advanced intensity and benefits.
Interval training has been documented to be one of THE most effective cardio training methods, and Interval Max is the best of the best. I-Max also gives your thigh muscles a great deal of conditioning as well with all of the jump-oriented "plyo" work.
Go for it! Very good investment!
Annette