Summary: I owned two of this and I can say that is the only mouse I can use for more than two hours (many times 8 or more). Ergonomics is fantastic, but the wheel suck (too light, and after some time tends to act the switch). I had an MX400 which lasted 5 years, and had no issue at all. Note that the MX400 has the same exact shape of this.
Summary: In order to have 3dsMAX recognize the middle button (scroll wheel), i had to download logitech's propriety software and assign both the left and right scroll buttons to to function as if they were also the middle button. There's some issue going on with the actual middle button registering. In any case, now it works great!
Summary: I've been using this mouse every day for nearly 3 years, and I'm very happy with it. It fills the hand well, far more comfortable than cheap standard mice, and the buttons are well-positioned. It glides well, but I've had to glue two of the pads back in place. The fast-scroll button is great for long documents, and the forward-back buttons are really handy too (in the few programs that support them).
Summary: This is the perfect mouse for me. I am a heavy spreadsheet and word user, with lots of web surfing. I also review and superficially edit thousands of photos as part of my work. I prefer the corded as batteries always run out at the most inconvenient time. The ergonomics totally work for me, and the free-scroll wheel feature is a massive help, when dealing with long documents and zoom function. The one issue I have is that the device tends to be somewhat fragile.
Summary: A corded mouse was hard to find to replace my old one (a Logitech of course). I use digitizing software, and wanted one with more precision than that of my old mouse -- being able to point and click on something the size of the period in this sentence. This one jumps right past the point I am aiming for. I have tried adjusting settings through the windows control panel, changing mouse pads, etc. -- to no avail. The old, no frills, Logitech worked better!
Summary: Mouse is great - could be a bit taller from an ergonomic perspective, but otherwise great. The wheel is awesome. After installing the software I seem to periodically lose control of the mouse, forcing a reboot. I am using Win 7 64-bit. It might be the Microsoft IntelliPoint (my previous mouse) fighting with the Logitech software, I don't know. I would be surprised if it had anything to do with the hardware.
Excerpt: Corded mice are getting hsrder to find - this is perhaps Logitech's last corded mouse with the same features as the more popular cordless models. My wife likes the simplicity of a mouse that does not require batteries or battery charging.
Pros: Accurate Tracking, Comfortable Design, Fast Response, Glides Smoothly, Great Features, Simple, Works day in day out