The major new feature of Firefox 3 Beta 2: Improved autocomplete in the address bar.
It's quite stable on Windows. I'm finding it's actually less stable on my Mac than Beta 1 was, but it's still stable enough to use as my main browser until the next release comes along, which Mozilla says will happen in February. Beta 2 freezes up a couple of times a day on my Mac. Beta 1 froze up only once or twice a week. I'm looking forward to Beta 3, when we'll hopefully start moving in the right direction again.
The new feature is kind of neat: Mozilla enhanced the autocomplete tool, which Firefox uses to guess the URLs you want when you start typing in the address bar. In Beta 1, Firefox searched your history, bookmarks, page titles of places you've visited and bookmarked, and bookmark keywords and tags to try to guess what you're looking for. In Beta 2, Firefox spruces up the dropdown from the address bar that Firefox uses to show you the pages it guessed. The dropdown now has a horizontal rule between entries, it shows the title of the pages it's suggesting, and it highlights which parts of the page title or URL match the entered text.
Autocomplete works quite well, and it's a terrific way to navigate the Web. Many of us have gotten used to not bookmarking our favorite sites -- we either remember their URLs or just run the same Google searches over and over. Autocomplete makes the same principle local; it's like Google for your own search history and bookmarks.
The Places feature, new to Firefox 3, combining bookmarks and browser history, is enhanced to improve search and adds a Smart Bookmarks folder on the browser toolbar, displaying most visited sites and recently visited sites, along with recent tags. My most visited site is Twitter. (Actually, Twitter is my top three most visited sites. How embarrassing! Next is Google Reader, followed by the InformationWeek Blog. The InformationWeek home page isn't very high on the list at all -- #7. That doesn't mean I don't love my job, it's just a reflection that I read InformationWeek mostly through RSS.)
The downloads window in Beta 3 has been enhanced, showing you the domains from which the file was downloaded.
The biggest change for me personally in Firefox 3 is the way that it now handles page magnification, introduced in Beta 1. Previously, Firefox magnified just the text on a page when you hit Ctrl-+ or Ctrl-- (on the Mac, that's Cmd-+ and Cmd--). In version 3, Firefox changes the size of the whole page, with all the elements shrunk and enlarged proportionally.
The new beta of Firefox also has new security features.