Used this for years and have never been any problems with it! Ergonomic, which is good if you are struggling with mouse arm, etc. Has big hands, which means that I must have your palm relatively far behind, for steering control trackball with your fingers, which means that I do not relax as well off as I wish. Seems like it's better for people with normal / small hands. The ball works well, but can be somewhat slow and jerky scrolling in time, especially at small mouse movements. Works for both left-and right-handed. Missing scroll, and the small buttons at the side of the main keys is very knotete to use. Have never tried a logitech trackball (ball controlled with the thumb) but will believe you relax even more in arms about it. but it is however only for right-handers.