Not bad if you ask me.
Has anyone who reads given this a shot? It’s in beta (obviously not for everyone…) but it seems pretty stable. The only thing I don’t have is the delicious addon working. It’s not been updated for FF3 yet.
It’s got a nice interface (I like it better than FF2, and I loved that interface), it’s pretty fast, and it just works. I’ll keep using Flock as my main browser, but it’s always a good idea to keep another one around for emergencies… :)