We have 2 also. They were supposed to help the boy to calm down when he was feeling out of control and angry. It is like giving him a shot of speed. It rev's him up terribly. She loves it because the one she has has the counter on it, she likes to make a game of it and see how many jumps she can do at one time, the most was around 1500 I think.
They are fun for everyone. There are tons of exercises the kids, or adults, can do on them. You don't need the rail on it, it kind of gets in the way and we removed it. We put it in the middle of the floor and they bounce for quite a while, but he does seem to be wound tighter than ever afterwards, she is not effected like that.