Mozilla Firefox 5 is out today, a few days early and just 3 months after Firefox 4 was released. Mozilla has adopted a fast-release platform, so perhaps we should expect Firefox 6 in a matter of hours.
After reading about Firefox 5, I would have installed it hoping for the speed improvements alone. There are a few other enhancements. Striving for even more of the minimalist look, there are even fewer buttons showing when 5 is first installed. Everything can be tweeked to your preferences, and a few minutes checking out the options should leave you with the custom look you like.
So far, Firefox 5 is really, really fast and I like it. Developers, just don't change over the IE pinned sites "feature" (my most hated thing about Internet Explorer 9) and I might just stay with Firefox for a while.
Mozilla Firefox 5 is available at FileHippo.com now, or at getfirefox.com very soon.