[RayChuang88]

While the original iPhone was a breakthrough, the real breakthrough for the iPhone didn't happen until the iPhone 3G arrived in June 2008, which added the App Store for third-party apps and added GSM HSDPA support for much faster data downloads (for its day).

[USNBandit]

The breakthrough wasn’t the gear, which all works and is pretty slick. The genius is the iTunes Store and the App Store. With immediate gratification, who can resist a $1 song or a $5 app?

[Swordmaker]

While the original iPhone was a breakthrough, the real breakthrough for the iPhone didn't happen until the iPhone 3G arrived in June 2008, which added the App Store for third-party apps and added GSM HSDPA support for much faster data downloads (for its day).

i can agree with that thinking. Steve Jobs was wrong to not allow downloading apps onto the iPhone directly and he admitted as much. However, the multi-touch interface, dropping the keyboard, and must of the buttons on a phone were major changes in thinking on phones. The limiting of the iPhone to WebApps. They worked, somewhat. . . but not as well as native apps on the iPhone 3G and later models would work later. Here is a graphic that really demonstrates the sea change that occurred with Steve's keynote: