Just as with it's software, Microsoft has copied someone else's design (in this case, Logitec's Trackman) only to create an inferior product. The construction and plastic are cheap and toy-like. Right out of the box, the ball movement feels sticky and makes an annoying scraping sound. Others have complained about it collecting gunk too quickly, but I frankkly wonder if some good greasy gunk might actually make it smoother. Total waste of money in my opinion.