The iPhone just works. Although, not perfect (no phone is), it is seamless. The app store was built around ONE phone with ONE screen size which makes the apps ideal. If course, with the iPhone 5 there is now another screen size and the apps are being optimized slowly for that phone as well.
I am one of those people who are not biased against something I don't use. I played with all the new popular Android devices before I upgraded my iPhone 4 to the 5, and I couldn't get over the cheap plastic feel of the Samsung phones, the unrealistic overblown colors of the screen, and the overall experience.
For me, the iPhone does what it is suppose to do.....and does it the best. The best part of the iPhone for me is the size of the screen (width of the phone). The phone still feels like a phone and not a small tablet. I also don't think the quality of the hardware can be argued. Nothing comes close to the feel of the aluminum and glass.
**No offense to Android phone users. This is just my honest opinion.