Hey guys, I just received my "bean" just the other day and I LOVE it! It is much more stable than the ball. I put it on the floor in front of the tv and do crunches while watching a favorite program and the time flies by and the burn sets in.
My MIL has one and she is disabled and says she has no problems exercising on it and loves it. Well at least that is what she said when she first got it, haven't heard anything about it lately.