I really like mozilla, but its missing some key features that I use all the time. First, in IE when you open a new window you get a copy of the same page but ALSO the back button history thread from the window that you hit control N in. This is great for things like if you are entering in order information in a website, but want to go back to a previous page without losing where you are, open a new window THEN go back.
I realize some people like a new window to open to a blank page, but I'd at least like the OPTION to do this in mozilla.
Second problem I have with mozilla, in passworded (the kind that pop up a password prompt window) sites many times it repeatedly asks for a password even if you enter it correctly, the same sites in IE dont. In addition (actually this makes the previous problem really nasty) when a password prompt comes up, you can NOT do anything else in mozilla but put in a password, even if other windows are open. In IE you can still do stuff in other windows and come back and do a password in. In mozilla if it gets stuck into an endless password loop (which can happen even if you hit cancel) you can't do anything else but kill the task since you can't access the menu, or click close window or anything else.
Were these 2 problems fixed, I'd use mozilla for my primary browser, but until then I just use it occasionally. It IS quite handy if you are going to a site (like some game review sites) that have tons of popups.