When the iPhone shipped to customers on June 29, 2007, the first generation of the device that would change the world was missing a lot of what we now expect in an iPhone, but it set up the road map for Apple that continues to this day.
Though Apple co-founder Steve Jobs unveiled the iPhone at the MacWorld Expo on January 9, 2007, it would not be until Friday, June 29, 2007, that it officially went on sale. You had one choice in cellular carriers, AT&T, and though it did not support the then-new 3G network or have any apps, it was described as "revolutionary" and "game-changing" by the press.
Everybody else has talked about the amazing touchscreen, or ground-breaking telephony, or even the flexibility of the internet with you at all times. But, there were practical reasons beyond just tech fetishism to get an iPhone in the early days, though.