The UI between 1.0 and 1.5 are almost identical. The new update system and options dialogue are excellent. It is generally all around faster, especially the back and foward buttons. Other than those, there is greater support for several xml formats, most of which I'll probably never see(i.e. svg). Drag-and-drop-tags is fun too.
Oh, yeah, and about half of the extensions I used to love (*cough* greasemonkey!) don't work. And my favorite theme. That kinda stinks.
Technically, there is a
list of new features, if you're interested.
Personally, I haven't run into any bugs. I wonder what the big deal is...
Strangely, for some intangible reason, I've become addicted to Fx and surfing the web all over again...
:firefox: