Firefox 3.5 has a number of new features to it including compatibility with some new HTML5 tags, a Private Browsing Mode, better Javascript performance, and a lot more. There are also extension incompatibilities with the upgrade so if you’re migrating a profile to 3.5, your extensions might be disabled until they’re upgraded to 3.5. Check out a lot of the changes in Firefox 3.5 with the release notes. It seems like things are running faster, snappier, and smoother with the 3.5 upgrade, so it seems promising.
If you want to see how Firefox 3.5 stacks up to other browsers, you can take it for a spin and put it through Peacekeeper, the browser benchmark system mentioned previously in my article on benchmarking.
With the release of Firefox 3.5, they’ve also redone how the Add-ons catalog appears over at Mozilla.
Check out Firefox 3.5 yourself.