It is a great and outstanding mouse, and you will be delighted with the ease of operation, the convenience of the placement of buttons, the ergonomic design, etc. I have carpal-tunnel syndrome, and use this mouse with no pain!
Buy this mouse . . . you'll love it as I do.
Other reviews here note driver and battery problems, but I assure you they are isolated incidents. Logitech has always produced quality drivers for every MS operating system and for the Mac.
One other review notes the wheel difference between Logitech and Microsoft mice. The Microsoft wheel spins with much less effort than do the Logitech mice. I actually much prefer the slightly more resistent wheel of Logitech devices because I find I over-rotate much more frequently with the Microsoft wheel tension being so loose. It's really a matter of personal preference, but I thought it would serve to clarify that point so the actual difference is known.
Overall, I can't wait for an optical cordless mouse from Logitech so I can run right out and buy it. As an IT professional, I rely on Logitech input devices quite heavily because of the quality of the entire product line.
You'll also notice that Microsoft products are very consistently priced higher for the same basic list of features, which is yet another reason I stick with Logitech.