Ah, you haven't tried at OSH.
As soon as VZ gets the iPhone, they'll suck at OSH too... Here's how I know:
1) In 2007, I got the iPhone a week after it came out and went to OSH with it a couple of weeks later. It worked really well. There were very few iPhones out on the street at that point.
2) In 2008, seemingly everyone had an iPhone, and AT&T was utterly useless at OSH because the network was completely overwhelmed. It was taking 3-4 hours to send a text message, and make a call? Fuhgeddaboutit.
3) In 2009, AT&T responded by putting up temporary towers at OSH. The service wasn't great, but it was WAY better than 2008. Texts went through right away, and I was usually able to use the phone OK.
When Airventure isn't happening, AT&T works just fine at OSH. So, when VZ gets the iPhone, I expect that they'll get stomped at OSH as well.
As much as I hate AT&T sometimes, their network really isn't as bad as everyone says. I switched from VZ to AT&T in Feb. 2006, long before the iPhone announcement, and there was a noticeable improvement in the number of calls I dropped (or, rather, didn't) and the areas where I had service (remember, I'm all over the country). It wasn't a huge difference, I might not even call it significant, but it was enough to be noticeable. It's only after the iPhone came out and they got clobbered that it started to get bad, and they've made a lot of improvements recently (last 2 years).
Every network is going to have dead spots - That's just a fact of life. So, there will be anecdotes about how good or bad anyone's service is based on individuals' own experiences. IME as someone who is traveling around the country all the time (I've been in all 48 states multiple times within the last 3 years), both VZ and AT&T are the only truly nationwide networks, and both are close enough to even that it's not worth making your decision based on the network unless you don't get any service at home.
I do expect AT&T's service will get better after VZ gets the iPhone, mainly because I'm sure a lot of folks will jump over to VZ at that point, whether the grass is really greener on the other side or not, and that'll relieve the burden on AT&T's network. I hope VZ is ready for the onslaught, or their network will suck worse than AT&T's does now...