I hate AT&T with a raging passion. My iPhone's data plan is in reality 40% of the data plan. The other 60% of the time my phone doesn't think I'm on the internet even though I have full bars and the 3G icon.
I just started a new contract, and I'm on CalTrain the other day, minding my own business, when this guy next to me has two calls drop on him in a row. He has an iPhone. He mutters, "Gawd, AT&T sucks," and everyone around laughs.
It's now conventional wisdom that AT&T has awful cell coverage. It's especially bad in the Bay Area, but it's bad everywhere.
I think we need a new term other than "coverage". In the old days, "bad coverage" means a place where there aren't enough cell towers around, where you're not getting any bars.
Nowadays, even when you're downtown, surrounded by farms of cell towers, getting full bars, your phone will still magically not work.