I just upgraded to Firefox 1.0. This was, initially, a rather painful thing, because it nuked all of my bookmarks, forgot my font/color/etc preferences, lost my plugins, and themes, and generally irritated me.
Having wasted a great deal of time, I have restored my bookmarks to their former glory, and mostly reinstalled all the doodads and geegaws that I had before.
Then someone introduced me to the new RSS functionality. As Junie B would say, Wowie wow wow! So, I can bookmark an RSS feed, and that gives me a list of recent articles. I can then “Open in tabs” and get, for example, all of the day’s Slashdot articles, one in each tab. This is so very cool, it almost makes up for the slash-and-burn nature of the upgrade itself.
I’m told there are other things, like the new search functionalty, that are wonderful. I don’t actually find the new search functionality particularly useful. Perhaps I’m missing something. In all, the 0.8->1.0 upgrade didn’t really gain me anything except a lot of pain and the RSS feature. Of course, the RSS feature is really starting to grow on me.