I use Chrome on my Win partition and FF on my Linux partition. I like the speed and tab handling in chrome, but I miss my add-ons from FF (NoScript, FlashBlock, Firebug, etc, etc.). But when I switch back to FF I have Chrome withdrawals. XD If Chrome gets similar add-ons I'll stop using FF indefinitely.
I was always a FF advocate, but with Google Chrome out I think FF will have their hands full trying to keep up.
I don't know if this is the case for everyone but Google Chrome is notably faster than Firefox for me.