Mozilla really screwed up both their long-time users and new users. There really haven't been good improvements in a long time. Most of their time has went to making it more Chrome like, and playing with version numbers.
I've seen many old Firefox users change their engine, on top of those that have been using IE. They aren't using Firefox, they're using Chrome or
RockMelt now. Especially RockMelt is an interesting browser - it completely abandons geeky stuff like NoScript or Adblock but instead caters to casual, normal people and how they use the internet. RockMelt has online Facebook friends directly on the site, along with recent news and updates from all social networks. It lets you easily add social bookmarks to sites like Reddit and Digg, along with sharing to Facebook and Twitter. Most people have been saying how wonderful it is compared to Firefox. It's an browser that actual
people want.