Daily Firefox user here. Switched back from Chrome a couple years ago and haven't looked back. Just seeing the comments here exasperates me... So for those who don't know, the Internet is heavily biased towards Chrome. Simple pages that should render no differently in FF than Chrome are often broken. This "Chrome is great, screw everything else" attitude is exactly how we ended up with IE and stagnation in standards/…
My personal biggest problem with FF is that it uses too much screen real estate compared to Chrome. For example, the tabs are really fat, and the address bar is much thicker, leaving less space for actual content. Perhaps FF should include a "look-like-chromium" option to win over users (since chromium is open-source, I guess they will not run into copyright issues there).
[0] https://addons.mozilla.org/en-US/firefox/addon/fxchrome/