The fact of the matter is that no single carrier has complete, sufficient coverage. It doesn't take a genius to understand why that is. Cellular service is still somewhat young for being a large infrastructural development. It has only been a little more than a decade where cellular phones and plans have become affordable enough for nearly everyone to own one.
I hear the same explanation from many people. "I use fill in carrier name because they have the best coverage in my area". Makes sense to me. Maybe those who got blindly sucked into the iPhone should have done a little more research and reconsidered what is more important, cool phone or reliable service. The only person to blaim is Apple for making a cool phone and establishing an exclusive deal with AT&T.
For myself, it just so happens that AT&T's service has always been perfectly fine where I live. I don't recall ever having a dropped call. It was a no-brainer for me to get an iPhone.
Although I tend to agree, but if people are going to these places and they enter their zip in and are insured good service, they should get good service. Rarely is this the case though.
Just recently since T-Mobile is pretty poor in this area our family went to Radio Shack to look for a decent provider and the guys ASSURED us that we get coverage with Boost and with no contract and decent plans they went for it only to not get coverage around our home's area.
Luckily they were easily returned but knowing my experience thus far with AT&T's DSL service it probably wouldn't be quite as easy with AT&T.