Here's an article with five reasons not to buy an iPhone. The most important to me is:
'VoIP,' or Voice over Internet Protocol.
For the uninitiated, this is the technology that allows you to make free, or nearly free, phone calls over any Internet connection. No, this isn't just geek stuff. Skype and Vonage (VG) are two widely used VoIP services, and there are now many more. The technology is growing rapidly. Free and open Wi-Fi networks are springing up like weeds in every city.
Sources close to Apple confirmed to me that the iPhone lacks VoIP technology. It cannot use Wi-Fi networks to make cheap calls over the Internet
(Stop the Presses: Steve Jobs has just revealed in a Wall Street Journal interview that he excluded VoIP from the iPhone because he didn't consider it a "breakthrough" technology. He has added, though, that a third party developer may produce a VoIP program for the iPhone in due course, to run through the browser.")
That's great news for AT&T, of course. It's bad news for consumers.
WiFi isn't universal yet, but it will be eventually and there won't be nearly as much need for the existing cellular infrastructure. The next phone I get will hopefully have VoIP built in.