Firefox 3.5 has a host of improvements, some the sort of thing people can notice immediately and some plumbing improvements that could help the Web in the long run. With the firefox 3.5 release, besides the usual performance improvement and bug fixes, it comes loaded with lot of features. It introduces support for HTML5 video tags, a first for web browsers.
Also, this time many more popular themes have been updated to support Firefox 3.5. Some of the Best are :