i am in VA and got cingular in 2005 when the service in the state was not really great (it was right as they were adding a lot of towers). had no service in a rural area here that i visit regularly but other than that it wasnt to bad, 6 months later when i go to the same rural area i now have full service, few months later they added 2 or 3 towers in my local area. my coverage is pretty good, the dorm i am in had bad service for everyone but ATT is one of the lowest ones, once i step out side or get to the ground floor though i get great service (stupid concrete and electrical wires).
my brother an i both have att (he has had it from before cingular bought att so i guess thats what 8 years maybe) and we have both had pretty good coverage and really good customer service when ever there was an issue where as my parents and sister have verizon and they have had sooooo many customer service issues.
the edge network is ok, with my iphone it is a lot faster than my old razr was with trying to go on line and heck its a freaking cell phone your not going to get dsl/cable speed (it was still plenty faster than dial up, way faster actually).
since you are in a city you should have good coverage, att seems to not penetrate into buildings, specifically ones with a lot of concrete or a lot of electrical, very well but its not to much worse than other services.
-matt