What people must realize is that this mouse takes some getting used to, especially if you have small hands like me. It took me at least 24 hours of play to start to get comfortable, but it really is worth persevering.
Once you get used to it, you'll wonder how you ever managed before. I have used it on pretty much every surface from the desk itself to a soft rubber nylon covered mouse mat without any difficulty. I would however, recommend a hard smooth surface to get the maximum from the technology involved. The technology on offer is, in my opinion, a little over the top. I have not managed to use the mouse set at 4000dpi yet, its way too sensitive, half that seems appropriate.
For those who complain about some of the buttons not being useable; the mouse is not designed for just FPS and caters for left or right hand use. So the buttons on the right side aren't supposed to be used by right handers. Even with my small hands I am able to use the side buttons with no difficulty whatsoever. This is partially due to the surface texture of the mouse. The texture coupled with the shape does help the mouse sit surprisingly comfortably in the palm of your hand.
If you are looking for the ultimate mouse, this may be it. Whether or not it's worth the high price is debatable though, but most importantly, does it make you play FPS any better than a mouse half the price? Not sure it does.