From iLounge’s review of the original iPhone:

There are some issues. First, there’s AT&T. If you’ve ever had doubts about the company, they’re not going to go away with iPhone: we’ve experienced very significant problems activating two of our iPhones, attributable not to iTunes but rather to AT&T, and its customer service has been atrocious. To say that they are making a bad first (or tenth) impression would be an understatement, and the shocking part is that in each of our situations (and others we’ve been following), the company can’t seem to do the right thing by people who are all but waving $1,500+ in fees in their faces. One wonders how bad the experiences need to be before Apple can hold them in breach of contract and work with other carriers instead.