The iPhone is an awesome device and will no doubt be a trendsetter for future devices similar to the way the iPod defined the way portable music should be. However, some iPhone owners have been discovering the cost of being on the bleeding edge of technology.
Currently, there are various bugs plaguing the iPhone's software. These bugs range from minor, application-specific bugs to somewhat major application crashes. We are currently hosting a thread for bug reports, in addition to an entire forum for tips, help, and troubleshooting. If you feel you have identified a bug that has not already been identified as confirmed, let us know (we'll pass it on to Apple once its confirmed as a bug).
In a non-bug related issue that potential purchasers should be aware of, with the iPhone being a GSM device, it can create interference with audio systems, speaker phones, and some CRT televisions. I have experienced this issue with my iPhone and my car audio system and with my computer's Harmon-Kardon SoundSticks. For more on this issue, continue reading (same issue, different phone).