I use it, but it's still loaded with bugs. Profiles get trashed. All browser windows and tabs close if one page crashes. Java applets will bring it down very hard and I have to restart Windows to get it running again. I've recently found out that the "hover" CSS properly is completely broken in 9.3, as links on my website will only occasionally underline on mouseover, with no rhyme or reason. The annoying "using double quotes makes the Alt-key get stuck" bug is still a problem -- it happended to me as I typed this. Arrrgh!
If it wasn't for popup blocking and the awesome "WebDeveloper" extension, I'd avoid it. At least now that it's going 1.0, there shouldn't be as many extension conflicts.
I still think it's better than IE, but I really wish people didn't drool over it so much. Firefox is just as screwed up as IE if you really work with it, and as a web developer, I'm a more than a little ticked off at how badly it works.
I have Opera on my machine, and I'm seriously thinking about buying it. It doesn't emulate "quirks mode" as well as Firefox, but "standards mode" is perfect and the browser is both rock stable and super fast.
IE is faster
It's about the same. Booting is slower, but rendering is the same. Opera is fastest at booting as far as I can tell, but renders slower and is not very responsive. But, they're
all pretty slow and use waaaaay too much memory. Firefox idles at 35Megs of memory on my machine, and as I'm typing this it is using 112Megs of memory. Cripes -- it wasn't long ago when Windows (or any other OS) didn't even use that much!