I was skeptical when I bought it thinking what kind of workout could you possibly get by using it...I used it 3 days in a row; each day it gave me a great ab workout. You can feel it working. I took a break from it yesterday and did normal crunches. I have to say that even though I haven't been exercising recently that crunches are something I've been able to do a lot of before feeling anything...well yesterday I felt the "burn" a lot sooner. I'm 5'8'' and not sure how much tension is supposed to be on the cords in certain positions, but it seems like the cords are kinda long. Not sure if you can buy shorter ones. But it works great. Not sure why the picture on the website says it comes with an 8lb kettlebell...the one in stores don't.