Today is "Upgrade to Firefox 3.5" day :-)
My upgrade went very smoothly, and one nice feature was it warned me beforehand which extensions wouldn't work with the new version.
Post-upgrade, it found a compatible version of Firebug, but I'm still waiting for updates of
- Bookmark Duplicate Detector
- Google Notebook
- Live Writerfox
- Microsoft .NET Framework Assistant 1.0
The following extensions work ok:
- English (Australian) Dictionary
- IE Tab
They reckon 3.5 is about twice as fast as 3.0. It certainly does seem snappier.