So, I downloaded it after reading an article on The Register. Oh sweet lord it's fast. Even on my five year old PC it's quick, and it doesn't have any of the memory leak problems that FF2 has. The only problem is that the Bookmarks Toolbar folder, which previously was hidden away subtley in my folder list, is now slap bang at the top. Given that this is where I keep my bookmarks that I don't want people to see, I feel a change around is in order.
Download it, it's super quick. It's the best thing to happen to me since Katy.