We have one. It takes an effort on DD part to make sure that we keep ball facing home at 12:00, and elbow slightly bent.
The greatest use for us is during a long offensive inning on our side. She will grab it when we get two outs, and make about 30 circles with it at full speed. It gets her loose quick.
Also, I would think that overuse would fight against I/R because of the hand path. That is why it is used limited for us.