I was in a 2003 Altima SL that had 85,000 miles on it and ordered a 2011 fusion SEL 2.5 liter in January and took delivery of it March 5th. Fusion now approaching 6k miles and very impressed with the quality, ride & design of car. Also I get outstanding gas mileage 32 +/- for town and 37 +/- on the highway (remember this is what I get and can vary by driver). Quality, ride & workmanship is far superior to the 2003 Altima. Although I dont know if the 2011 Altima has improved in these areas, doubt it though, its the same platform (reason I didn't look at Altima). I will say Altima overall was very reliable, time will tell on Fusion.
Design, workmanship, quality, ride and the gas mileage!
Noted by other people but the 2.5 liter engine can get raspy at 3500 rpm and hgher on hard acceleration. Not sure if it the engine itself or exhaust. Not a big deal or show stopper for me, in fact I don't even notice it now.