At work, I'm constantly taking my laptop in and out of its docking station and traveling around the building to various conference rooms and other offices. It's a pain to use the touchpad when away from my desk, and it's also a pain to carry a wired mouse and have it dangling all over the place and accidentally activating buttons when I'm carrying it around. One of my coworkers showed me this model and I immediately decided to get one myself.
The killer feature (for me) of the Logitech V550 is that it comes with three little adhesive clips. You attach one to the lid of your laptop, and then you can snap the mouse onto and off of the laptop in a flash. The buttons cannot be accidentally activated when it's clipped in. The mouse itself is fairly small but feels solid and comfortable in my large-ish hands. It also has Logitech's "Hyper-Fast Scrolling" wheel which I thought was kind of a gimmick, but turns out to be quite nice: you can use the scrolling wheel click-by-click as with most other mice, or press it to switch to a smooth-scrolling mode which is good for scrolling down long pages. You can also wiggle the scroll wheel side-to-side, and I have configured this to go forward and backward on web pages.I haven't had it long enough to find out how good the battery life is, but it's supposed to be many, many months, which is far better than other optical mice I have used.
So, if you need a mouse to use with a laptop that you're carrying around all the time, I highly recommend this one. I paid about $30 and I think it's well worth it.
