While reviews are typically a matter of opinion, not fact, I find most of the negative comments about this product to be wildly inaccurate. I have used this device on hardwood floors, tile, gym mats and currently use it on carpet and it has never skipped. It does require a certain degree of force and strength to begin with. So if you're unable to apply the pressure required to steady it then you're going to have issues. I do the advanced workout with it that includes my obliques and whenever I use it, I feel it in everything from my grip, forearms, upper arms, shoulders, chest and abs. Long story short: If you're not seeing results or it's too difficult to operate or too uncomfortable to use, then chances are you're not doing it right or not strong enough to operate it correctly or just being a diva (male or female) by expecting your workout to be comfortable. Comfortability and results do not go hand in hand in a workout. If you're comfy while working out, you're not doing it right and/or you're never going to see satisfactory results. Hence the phrase "no pain, no gain." I'm sure you've all heard that one.