As an experiment, I had switched to using Firefox once FF3 was released. I like the Awesome Bar, and the browser definitely feels a bit peppier than Firefox 2. The biggest advantage Firefox 2 has over Safari remains: the add-ons.
However, Safari feels so much faster than Firefox that I’m switching back because I find the basic browsing experience to be nicer. I still have Firefox around for the times when I really want to use one of the extensions… but the most important extension, Firebug, has been ably duplicated in WebKit’s debugger.
If you’re a web developer using the Mac, give the WebKit nightly a try and see what you think.
Update: I also wanted to note that I’ve noticed playing Flash videos in Firefox 3 was choppy. I don’t know who’s to blame (Flash or Firefox), but it works fine in Safari.