The iPhone boasts that it has the best touch screen interface available and i have to agree that it does. The screen is just so responsive and fast without lag or difficulties in pressing an icon. Also the iPhone has a good battery life in comparison to some other touch screen phone around.
That is why it is better than having a keyboard phone like the P1i or blackberries.
In addition the screen is better and sharper. The colours are better and much more pleasurable to use when viewing photos, vidoes or webpages.