LCD screen located on the underside of the mouse. This allows you to adjust all the settings on your mouse even without having the software installed on your system. If you use multiple systems, this is a godsend: your settings are ready to go whether you're playing on your laptop or on your gaming box.
If you're in the middle of the game and want to adjust your DPI? Flip the mouse over, make the adjustment using the screen, and then put it back on your mouse pad to play. It's easy to assume that an LCD screen on a mouse is a gimmick, but you get used to having it there; the last time I played Left 4 Dead 2 I used the screen to make a few changes to my settings, and then saved it as a new profile so I could switch back and forth whenever I need to, without bringing up the software on the desktop.
[...]This is, to put it mildly, a very good mouse. It feels impressive in your hand, has nine buttons you can program to your heart's content, features a built-in LCD screen that lets you change your settings or create profiles while in-game. It performs all the tasks asked of it admirably.