Well, I just got Firefox 2.0 installed and running, and here's my list of goodies and baddies about it:
Goodies:
1. VASTLY improved default UI. Tabbing interface is cleaner and better looking, though I'm somewhat disappointed in the omission of the standard, right-hand tab close button, which has been replaced with a drop-down list of open tabs.
2. Anti-phishing. This is a good thing for careless people, but for those that know what they're doing, it's useless.
3. Improved performance. The new Firefox came up from a cold start almost 30% faster than Firefox 1.5.0.7, and it also handles loading bigger web pages better.
4. Inline spell-checker. Again, a good thing for some people, but for spelling/grammar masters such as myself, it's useless.

It can get annoying, though, typing in a certain word that's not in the dictionary and seeing the red underline, a la MS Word, but, like Word, just 2 clicks and you can add it to the dictionary.
More goodies will be added later as I discover them.
Baddies:
1. Half of my extensions, including Tab Mix Plus and Fasterfox, are incompatible with FF 2.0. This is the biggest hit against FF 2.0 for me. People who load FF down with extensions will be disappointed to see some of their favorite extensions aren't compatible.
2. Incompatible themes. Because of the improved U.I., most themes I've used aren't compatible with FF 2.0. This includes Blueshift, which is my favorite theme, and I never used 1.x without it. I'm hoping a new version is released soon, because going back to the plain old default theme is somewhat painful.
3. No right-hand standard tab close button. As I said before, this is a disappointment, mainly because I've trained my hand over the past year and a half to snap to the right-hand close button. Hopefully when Tab Mix Plus is updated to work with FF 2.0 they'll include an easy toggle to restore this button without going into about:config.
More baddies will be added when I uncover them.
That sums it up for now, I guess. If anyone else has Firefox 2.0 installed, post about how it's been for you so far and whether or not you like it more than previous versions.
This post has been edited by Sir Modsalot: Oct 25 2006, 10:07 AM