This is a very nice tool and has a lot of potential. But I get kinda stuck in my ways and doubt if I'll be kicking mapquest to the curb quite yet.
A nice, big, clean, draggable (!) map from Google means innovate or be gone to Yahoo! Maps and Mapquest. The local search integration isn't that strong - a search for oil change gives me the 10 closest Valvoline stations and nothing else - but I'm confident that will improve.
What I am waiting for is the topo version of this. That would be sweet! No more paying delorme for wholly inaccurate mapping, streets that are not listed even though they have been there for 20 years, and of course the fact that they seem to forget about us in the Mac world...