Here at TUAW, we still hear plenty of complaints about AT&T's service (many of them actually directed at AT&T, but sent to us for some reason). But the Better Business Bureau says we're actually in a good spot -- AT&T apparently has the lowest amount of complaints from major carriers coming through that agency out of all of the various cell phone service providers. Note that they are referring to major carriers: smaller regional carrier Metro PC actually had the lowest number, but of course they don't service nearly as many people.
Verizon was second best among the major carriers in the US, then Sprint, and T-Mobile brought up the rear, with 26,387 complaints over the last few years. There's good news, though -- data from last year shows that 95% of the complaints to the BBB about wireless issues were actually resolved. So apparently the squeaky wheel does get the grease.
Obviously, there are a lot of factors here -- just because a company does or doesn't get a lot of BBB complaints doesn't necessarily reflect 1:1 on its service. But clearly not many of the people supposedly disappointed with AT&T have gone off to the Better Business Bureau for help.