I just bought a sensei, and recieved it yesterday. For the first time since I switched to left handed mice, I don't notice my mouse anymore. It's amazing.
The control I have over my games when using this mouse is the best I've experienced, and the control I have over the way the mouse behaves internally is empirically the best.
You can control lift off distance, mouse smoothing, mouse speed, etc.
The only failing of this mouse is one I can quickly get past: you have two dpi settings, instead of the industry standard of 5, and instead of flipping back and forward through the 5 options 1 step at a time, you flip flop between the two with a single button. For a great deal of games where the need to change immediately in game, this is actually superior and requires fewer button presses.
The only particular place where one needs to be able to change those settings at random like that is for those who are incapable of maintaining performance and need to be able to dial it down as gameplay goes down, or for those who just can't make up their mind.
I set mine at 1600 for desktop and games that are cursor based (WoW, Starcraft, etc.), with a DPI setting of about 4200 or so in games like quakelive or when I'm in a tank in BC2 or something, because seriously, those vehicles are intended to be sluggish as crap and it's a good workaround for those.
