You need to atleast go into the preferences to select extra lists (if you want them) and to disable whitelisted sites (also, if you want to do that since ABP enables "some" ads by default).
(I'd probably enable the whitelisted stuff... IF I wasn't more concerned about adware than anything else over ad-networks)
I've said this before but being a habitual user of noscript I feel that all I really need from an adblocker is to skip those annoying youtube commercials. Everything else noscript handles pretty well. So I'll have to see if uBlock can do that for me.