I'm liking it so far.I didn't care too much for the awesome bar(the new url search bar).If you prefer the old FireFox 2 one you can get an add-on
here that'll change it to look like the FireFox 2 version.I've read that there's some exploits that have been discovered in it already.I hope they patch them asap.
I'm still waiting for my old FireFox 2 theme to updated to work in FireFox 3.When I 1st installed it it didn't detect the Quicktime plugin, but uninstalling & reinstalling Quicktime Alternative fixed it.It detected the RealPlayer plugins so I didn't have to reinstall Real alternative.Chatzilla & NoScript worked in FireFox 3 too without having to wait until they were updated to be compatible with FireFox 3.
Tune if you go to the search bar in the upper right hand corner of FireFox you can select another search engine to be used when you right click in FireFox.If you want to add torrent sites search engines check out this
link.I couldn't find any on addons.mozilla.org.