IMO, it's a must have.  I also do yoga and love it, but this is athletic stretching and more STRETCHING than flexibility work in yoga.  When I do yoga, for example, I find my upper body not very stretched out.  I like that Stretch Max makes sure the entire body gets a thorough stretch, especially after some workouts that don't have as much stretching.  It's also, for me, faster than yoga, at just 20 mins/segment.  My shortest yoga is 30 mins.  Anyway, just my two cents, but it's definitely worth having and I do it at least twice/week with any rotation.
Carol