Been running it now for just over a day with no problems. Only problem I had was that my Mouse Gestures was not supported so I've installed a beta version but that seems fine. Does indeed seem a tad faster, some of the defaults in 3.5 are not to my liking so I changed them and you can add back the progress indicator back into the toolbar from the customise option - its not there by default. Skype is the only ad on that I want but still is not supported yet.
Must admit I still have IE6 which is only there for emergencies when FF wont display a site. I never use IE of any flavour if I can possibly avoid it.