The other day I was setting up my fiancee's laptop in our living room and plugged in my old "service-issue" Dell two-button mouse to do some casual Web surfing. I hadn't used that mouse in months, and right away I knew something was wrong. My first thought was "Hey, this thing is broken" but I realized I've just come to use my mouse a different way since I got my Logitech MX Revolution.
I have to admit that I was first drawn to this mouse because it looks flippin' sweet; it's like some kind of Batmouse. (Not a rodent that swoops down and eats itself, more like something that Batman would use. With his Mac, of course.) The sweeping flanges on its sides and black/gray glossy/matte materials with the chrome wheel buttons are downright cool-looking. But it's a different feature of the mouse - and you wouldn't guess it at first look - is what sets it apart.
The scroll wheel is a heavy piece of cast alloy that has two gears: a traditional "clicky" scroll-wheel gear and a free-spinning, smooth gear. The thing about the smooth gear is that the scroll wheel is heavy enough that you can really spin it; so getting to the bottom of that long email or scrolling down a zoomed-in Photoshop document is just a matter of a stout flick. Instead of the endless "scroll-scroll-scroll" fingerwork I'd been used to, the action is more like a "flick....aaand brake" maneuver. Clicking the scroll wheel shifts between gears, although in 9 months of using it I can say that I never use the "clicky" gear; the smooth one is way too useful across a span of applications, and it's very graceful and sensitive to use without being finicky.
This is the thing that I'm totally in love with; instead of a sticky, clunky wheel that you have to push and push on, you've got an intuitive, tactile way of scrolling through just about any document. The scroll wheel on other mice now just feels broken and wrong to me and I am convinced that there's no going back.
The software to set the mouse up lets you customize just about everything except for the scroll-wheel click movement, which is confined to "gearshift". Many people rely on this wheel-click as an "open in new tab/window" button for Firefox, so this might be a discouragement for some. I don't really use that too often so I never noticed.
The mouse also has a unique horizontal scroll wheel accessible with your thumb. I set mine to behave as an application-switcher most of the time (which I never use) and a super-handy zoom wheel in Photoshop/Illustrator (which I use all the time).
There are small back/forward thumb buttons on the left-side flange that can be set to work great moving between pages in a Web browser, between tracks in iTunes, or whatever you like per application. There is also a small button on top that instantly brings up a Google search (or Yahoo, or your choice of search engine) for whatever is selected. This is super-handy as well and I've come to use it all the time.
It charges via a dock that I have to remember to place it in at night; this has been annoying on a couple of occasions when I forgot to charge the mouse and couldn't just slap a new battery into it...but the mouse does charge fast, and disposable batteries are toxic garbage-generating, expense-adding annoyances that should be eliminated from all small devices IMHO so I like the rechargeable aspect. A handy LED meter on the mouse lets you know how your charge is holding up.
So there are my two cents...I am interested in other people's favorite mouse/trackball/tablet interfaces too...though this is my current favorite who know's what's out there that I haven't seen yet? So if you have a favorite input device that you'd like to share please leave a note and/or link in the comments!