I used to have PacBell / Cingular, and it's always been wishy washy. Down in Santa Barbara it was great, but anywhere else, it really sucked. Every call I'd make, over 30 seconds, would drop. So strange =(
But since I went to Verizon, it's been great. No more dropped calls! Well, very rarely.
The problem is, my dumb razr runs out of batteries in about 8 hours, less if I talk a lot. I always have to charge it in the car or midway through the day. Sucks when I'm out all day!
BTW: Apple is getting sued I think by Cisco for the iPhone now!