I did cardio kickboxing before I got sick. I did aerobics, so I only did a couple of days of the beginner/introduction video and moved to the advanced. It kicked my hiney - and I wasn't out of shape. I thought I was going to vomit. So, my advice is to make sure you work up to it. The advanced ended up being too hard on my knees and hips, so I went to intermediate. It definitely shapes and tones and promotes weight loss.
Also, when doing the punches I envisioned one of my exes. I was punching hard. LOL