I detest it, because it only boosts the egos of Firefox "elitists," and I hate it when people preach their precious browser. Seriously, I don't care what browser you use, and therefore nobody else should. Sure, I feel Firefox is advantageous over Internet Explorer (even though I don't use it on a regular basis due to lack of sufficient memory on my weak computer), but you don't need to be an elitist about it, damn it. Everytime I see a Firefox banner in someone's sig my respect lowers.
Switch to it if you like, but please don't babble on and on about how it's superior to Internet Explorer. All right, we get it that it's better than the ill-conceived browser, move on and talk about much more interesting things, like myself.
Besides, Internet Explorer only sucks when you do things you're not supposed to do in the first place.