Is your rubber overmolding cracking on the sides? Mine spent a very hot summer cutting 4" and 6" PVC pipe in dirt trenches, and it's cracking. I've thought about taking advantage of Milwaukee's 5 year warranty to get it fixed/replaced while I still can...
No, honestly other than being fairly dirty at the moment, it still looks brand new. I usually try to wipe the tools down after each use, but I'm ashamed to say I've neglected to do so with my impact driver, Hackzall, and Sawzall recently. My Sawzall actually still has mud/dirt on it from cutting pvc in a ditch when installing a drain line last fall. The Hackzall hasn't had near the use as the others though, and is in fact the newest Milwaukee tool I've bought at around 2 years old, and it's had the least use. All my stuff lives in my shop either on a rack I made or on a shelf on my build table, so it's lived a pretty easy life when not in use. The most damage any of mine have are some heavy scars from falling off of ladders and such. I've had one person I know use the Milwaukee warranty (I can't remember what the issue was) and it was a painless process as I recall.