Yesterday, while waiting for an appointment, I overheard a conversation from a lady telling a complete stranger her feedback on her iPhone 3G. She said she loves every aspects of the iPhone besides the actual phone. She "recommended" that total stranger to wait until the next generation when Apple gets the phone straightened out.
A few thoughts came to my mind after hearing this. First, most people do not realize that a smartphone is really a small computer. For every function to work, it must be written as an application, hence a "phone" application or "email" application, etc. The only difference or challenge, is to include a baseband software so the device is always keeping the phone application running with minimal power-draw while it anticipates calls, SMS or VM alerts.
That said, if there is a complaint against the phone application, most of the functionality can be improved or enhanced over time via software or OS updates (unless of course, if you have a complaint against hardware for example: loudspeaker is not loud enough or the voice quality is always choppy because of a bad phone modem or poorly located internal antenna).
In all fairness, I feel the Phone application in the iPhone is pretty well written; I distinctly remember coming from a Windows-Mobile 6.0 device and the usability was night and day. Overall, iPhones onscreen GUI is large, well thoughout and responsive. Its easy to dial or browse using your finger tip whereas my previous smartphones like my AT&T 8525 or Treo 680 pretty much required a stylus to provide precise input on the touchscreen. Although when compared to my Nokia N95-3, I must say that the Nokia is a step above in terms of its phone application. Of course, having a numeric keypad helps and having louder volume and dedicated phone/end key just gives you that much more functionality as a phone.
As for me, I am not a big talker on the phone. My rollover minutes are always racking up in thousands. For the small amount of phone calls I make, I find the iPhone tolerable. Its ability to aggregate and make good use of the meager EDGE or 3G data pipeline over other powerful applications is what impresses me. So, I guess no complaints here.