So, I'm at a friend's house and she has a device called the Mini Ab Circle. Seems like a cool little gizmo that allows you to do various simple movements for working out your abs. But, here's the downside: it's hard on your knees. Well, it's hard on my knees, and I don't have particularly troublesome knees. I probably tried it out for about 4 minutes, doing maybe 6 different moves. And when I stopped, owie. My right knee really was sore. The reason for this is that all of the exercises have you down in a kneeling position. So while I love the idea that you can just do these repetitive motions while you're watching TV, I'm not so sure I could stand to do it regularly if it was hurting my knees like that. FYI, the mini machine is $99 and the larger version is $199. Not too bad, but WAY more expensive than the Crunchless Abs program.
So there are two upsides of the Crunchless Abs program: very inexpensive, and really low-impact on your body. You get great results on your abdominal core without stressing other joints and muscles in the process.