I think that it does help, but it isn't necessary. The concept of the ab roller is that it puts your body in a position where you have to use your abdominal muscles to stay up. This same thing can be achieved with the plank exercise, which is when you put your body is sort of a push-up position, but with your forearms on the floor (the rest of your body is in the traditional "male" push-up position). You hold that position for as long as you can (usually those who aren't used to it can only hold it for a several seconds, but a goal might be to build up to holding it for a full minute). This exercise is great for the abs because you have to contract them to stay up and balanced. Also, it doesn't tax your neck or shoulder area like traditional crunches. In short, the ab roller is emulating the plank concept and will probably help some; however, I feel that it's an unnecessary piece of equipment (I know---I bought one a couple of years ago and it's gathering dust in my closet).
