I'm planning on buying this. My only concern is that the vertical side mouse buttons are going to feel too weird after being Logitech exclusive for the past couple years.
This probably won't be my main mouse either. I use the MX Revolution as my internet/general task mouse and switch with my Logitech G (I forget the number) for games. This would probably be my new gaming mouse.
I use the Logitech G15 for my keyboard. It's so damn nice and I like having a screen here. It interacts with games too (like Crysis Warhead) but it's basically useless because you have a hud...