yes and I put it away! I'm 41 and an old runner, gymnast and skier. This is a program that is really heavy on the knees. I couldn't do it for any length of time. After a week, I thought, screw it. My knees couldn't take all the lunges. I can see where it works. Jumping jacks!
I'd be worrie about my knees, too. I still can't walk up a flight of stairs by bending my right knee since I injured it last fall. I have to take each step with the left knee and keep my right one straight.
I own it and have done it many times. I usually do one segment and follow with some elliptical or other cardio. You don't have to do the full impact, you can do the beginner modifications. It's effective.