In the past, whenever I have tried a Logitech mouse, it never seemed to fit my hand right, so I was expecting the MX518 to be the same way. However, I was surprised to find that the MX518 fit my hand a lot better than the Microsoft Intellimice that I had come to prefer. At first, I didn't even know if the 1600dpi would make that much of a difference over my 400dpi Intellimouse when playing a game, but I was wrong. The difference is almost night and day. The mouse was much more sensitive to my movements and took awhile to get used to. However, after I got used to the sensitivity of the MX518, I noticed that I had seemingly become better at the games I frequently play. After I experience this improvement, I switched back to my old Intellimouse, just to see if it was the mouse, and sure enough, I did worst in the games with the Intellimouse. The best thing about this mouse was the fact that when I pressed a mouse button during the game, it responded almost immediately. With ever other mouse that I have used, there was a short lag from the time I pressed the button to the action actually occurring. This is probably the feature that attributed most to the improvement in my gaming abilities. In games like Battlefield 2, this was never really a problem. However, in games such as Unreal Tournament or Red Faction, this delay caused many deaths and much frustration for me. Another nice feature of the MX518 is that you can adjust the sensitivity of the mouse with two buttons that are in front of and behind the scroll wheel. It was extremely useful to me to be able to adjust the sensitivity during different times of the game, without having to mess around too much.