Now that Mozilla as finally released Firefox 3.5, I know that many of you will be eager to take it for a spin ... but be careful as upgrading might mean you end up with fewer features, not more.
I'm getting report from a number of Hardware 2.0 that Firefox 3.5 is incompatible with a number of popular add-ons. I don't have a list affected add-ons, but I suggest that if you rely on add-ons to improve your browsing experience, then you should probably take things slowly and test.
If you find that a must-have add-on is hosed, you can always download the latest version (3.0.11) from here.
I suggest you also read the release notes.
Tip: You might be able to tweak an add-on to work by following the instructions on the Mozilla knowledge base ... it's quite involved and there are no guarantees that the add-on will work, but it's worth a try!