Screen resolution for one. Its beyond what our naked eyes can properly digest - beyond 200 ppi. Unlike current smartphones on the market save HTC's recent attempt, none has even come close.
Natural Touch i call it to how the Mac OS-powered icons and menu graces the large screen so dynamically and realistically.
Large 8/16GB storage for a third wow factor as closely followed by the rest of the world.
Sophisticated image color balance of the 2MP camera which surprised me with her intelligent rendering of each frame I took. I must say its good. The overall built quality is staggering, almost on par with the blackberry (e.g. 8120) who still insists that their phone be made in Canada or Hungary today.
Lastly, the OS, which makes boring tasks of calling or entering data so silky smooth.
All the above has clearly differentiates the iPhone from another off-the-mill squeaky smartphones production plant owned by giant like Nokia.
Good enough reason to get one?