I've had my iPhone since the day after it came out, and I finally started having some issues with it. It randomly drops the signal and becomes inoperable in terms of data and voice service, and I would have to either reset it or toggle the Airplane Mode. I am a frequent user of the data network and when it randomly drops on me, I can no longer communicate with those on my buddy list, or check my email, etc.
I guess that having bought a "first batch" iPhone was destined to have problems at some point in time, but then again, this is technology - which is never perfect. I'll be making an appointment at the Genius Bar so they can replace my phone. There are other small annoyances such as my speaker volume being irrationally low, and that I can't ever hear it ring in any normal circumstance, or when I'm using it as a speakerphone. The UV coating on the camera lens plate also wore off and now my pictures are always blurred and overexposed. This is a big no-no for me as I love to take the best photos possible.
I've grown to be sentimentally attached to my iPhone and I didn't want to exchange it, but this has gone overboard and now it's a requirement for me to take action. I still love my iPhone, no worries!