While A-GPS and 3G are advantageous, part of the massive hype is just the fun of massive hype.
I didn't need a new phone by any stretch of the imagination, but you can't deny that the iPhone is an enigmatic and remarkable device, and I (never been an early adopter or wait-in-line type) decided to get in early just to enjoy the experience for once.
Now, the majority of things I felt were lacking in my iPhone previously have been addressed in a new device. I'm totally happy I bought mine, as I'm sure millions of others are.