Logitech MX518 Optical Gaming Mouse

The design of the mouse is also excellent. The buttons are positioned so that you can't accidentally press them mid-game (as I've done with a previous gaming mouse I owned).

Verdict: It's a bit expensive but if you're a heavy FPS gamer then I think this is just about the best mouse you can own. My Counter Strike kills have improved dramatically since I bought this.

General info on the mouse:
Just over 13cm long, 6.5cm wide, and just over 4.5cm high. Not heavy. Fast response time.

Problems with the mouse:
The biggest issue is whether you will find the mouse comfortable. Logitech mice have quite a large but comfortable hump. If you have small fingers then this is the best gaming-standard mouse available (at time of writing). The only other company who I'd consider buying a gaming-standard mouse from, Razerzone, sell mice which are substantially longer, with less hump. My fingers can not reach to the mouse wheel on Razerzone mice. However, if you have large hands then your little finger is likely to trail on the desk when you use this mouse. There is no groove on the right of the mouse for your little finger to sit on. This is only a problem if you got medium-big fingers (for a guy).

Other considerations:
The Logitech mouse lets you set it's sensitivity to multiples of 50. I normally have it at 1000dpi. I never use the mouse at 1600dpi for two reasons.
Firstly it doesn't cope well with major accelerations at it's maximum dpi. So if I turn rapidly and suddenly it will struggle. At a lower dpi (1400 or below) it is fine - no problems even when I do fast spins.
Secondly if you want to keep the amount of desk space you use to turn 180degrees the same, the higher your mouse dpi, the lower your the in-game sensitivity will need to be set. The smaller the number you are changing the higher the % change of the number. With older games, at 1600dpi I am making 3% changes with each setting change, and this is too inaccurate.

Summary and few extra points:
why buy?
- play FPS games
- happy to splash out a bit for a nicer mouse which performs well at 1400dpi or less
- need to change your mouse sensitivity on-the-fly. if you can't think of a situation where you need to then you don't need to.

why not to buy?
- large hands/fingers (look into Razerzone)
- already have a 1200dpi mouse (if you think you need a 1600dpi mouse then get a mouse-mat and/or learn to aim)
- want a left handed mouse
- want to do fine-detailed 'art' using the mouse (go buy a graphics tablet)

neat things which are not really in the equation:
- there's a quick-program-switch button on the mouse that I rarely use. Alt+Tab on the keyboard works fine for me.

Final advice, if unsure it's for you, there's several mice of identical shape (check the logitech website) ... find someone who has one and check you like the feel.

Unsure whether to get this mouse or a razerzone, and can't do the piece of advice above? Then go by the handsize advice I gave earlier. Still unsure? Then get this one.

4 stars and not 5 because you can't change DPI by less than 50dpi in a go (not a big issue) and the black is coming off on the circular "logitech" logo below where the palm goes. I'd rather the logitech logo was plastic like everything else and thus didnt lose it's paint like it is now. Good buy. Am happy with it.

By the way, on-the-fly sensitivity changing is adored by some, unused by others. Personally I dont use it. It's not essential in any way.