Used this mouse for 2+ years. It was a great mouse, the only complaint that I had was that it was rather small. My hand would constantly cramp up after playing for awhile. If you have smaller hands this may be the mouse for you!!! I stuck with it for so long b/c I got used to it in FPS games. Switched to the steelseries kana and have not looked back.
I wouldn't call it small, but it is a little shorter. It can actually be wide with the different pieces that swap out. The Kana is actually a little small overall to me compared to the Sensei from SteelSeries