I'm not sure how Cingular's service is in St. Louis but here in Chicago it's been flawless. I've had no problems with the network anywhere I've gone in the nation and have had no problems using it in The Netherlands, France, Italy and Germany as well. I honestly can't believe there are so many Cingular haters out there.
I live in St. Louis and I haven't had any problems with Cingular's service. The only times it doesn't work have been in tunnels or *deep* inside buildings. Nothing out of the ordinary, really.
And if the monthly cost of service for the iPhone is free/cheaper, I'll be forking over for an iPhone almost immediately. The cost of the plan (not the phone) is what will keep me from buying one.