It just me or does the GUI look like a direct rip of Chrome? And I like how they assume I want my tabs at the top when they've been on the bottom for years. Can't say how the speed is, haven't used it much yet.
Chrome is fast no doubt. But... as you said the add-ons/extensions are few and far between. Google also claims to use less RAM but that wasn't the case when I tried it last (build 10.xx).
I will say this it is smoking fast, If google wants more peeps to use chrome, then they need to make it more robust like FF is. I love the new look of FF4 (been beta testing for a few months now) it keeps everything nice and tidy and simple.