Wow. This is actually... nice.
I'd been using Mozilla 0.9.6 for the past few months, mainly because new Mozilla RPMs would break and I'd just have to remove them and go back to 0.9.6. Well, today I decided I'd upgrade. Moved the ol' .mozilla directory, rpm -e'd mozilla-0.9.6-0 and installed the new stuff. I needed to download 2 RPMs from Mozilla - mozilla-1.0rc1-0.i386.rpm and mozilla-nspr-1.0rc1-0.i386.rpm. The second one contains some files that used to be in the regular mozilla RPM. Anyway, once I installed those two, I launched Mozilla. Wahoo! It worked. I changed the theme, set my preferences, and quit. Then I put my bookmarks file in the new profile directory and fired it back up again.
I have to say, I only notice a little bit of an improvement in launching time. It's now up instantly instead of "almost instantly". But my computer is stupidly fast, so that's not really an issue. What I do notice as much improved is the interface - it seems to react a lot faster now. Maybe it's just me being optimistic, but it just feels better.
Rendering looks pretty good. But it has for quite some time now. It does seem to be getting a little faster.
One annoying thing is that if you're typing in a text entry area (like this one), you can't hit CTRL-N and have it bring up a new window. It just ignores it. However, if you hit CTRL-T, it does bring up a new tab, which is handy enough.
Anyway, so far I'm liking it. I'll keep posting and let you guys know.