Overall, a very good mouse. It's large, so maybe not people for hands much smaller than my own. For people with hands like mine, it's extremely comfortable and the additional buttons are located in a place that feels very natural. It also seems to be built to a fairly high standard. For the price, it's hard to beat.
It comes with a PS/2 adapter, which isn't anything special but does at least free up a USB port. My only minor complaint is that the sensitivity button unfortunately doesn't give you any feedback telling you what setting you are adjusting it to.