I've noticed that Firefox was updated to 14.  I couldn't help but notice because the user interface (UI) changed in a negative way on the update.

Another problem with Firefox (especially on Windows) is the update mechanism.  On Windows, it's an intrusive process that can't be scheduled, and on all platforms, there's the near-likely chance that an extension will be incompatible or that the UI will suddenly become just unfamiliar enough.  Regular updates are generally a good idea, but Mozilla is pushing the experience to the limit of user patience.

A former Mozilla employee made that argument shortly before Firefox 14 came out.  A few days ago, the story got coverage in PC World and ComputerWorld.

Keeping up with and keeping ahead of the competition is okay, but Web browser choice is at last back, and there are some reasons why us Firefox users don't just switch.  (Personally, I keep Opera, Chromium, Dillo, Lynx, and Links for regular use as well as Firefox.)