I just upgraded to RC2 from b5. I was waiting because I didn't want my addons to be incompatible, but most of them work now and I forced about 5 of them to work by overriding their compatibility.
That auto-suggestion thing kind of pissed me off at first, I didn't like it. I got an addon to make it look like the Firefox 2 drop-down bar, and now I like it. It's much quicker now as well. I believe the addon is called "oldbar."
Also, if you use Firefox you need to get NoScript (disables all scripts - you can toggle on and off and change what it allows easily), Yet Another Remove it Permanently (allows you to permanently remove anything on a web page - no more annoying text ads!), Redirect Remover (removes redirects when you click on links), and of course Adblock + FilterG.