You tap right there on the screen with your finger. There is no indirect manipulation via softkeys. This means a single touch to call someone. On a softkey phone you may have to scroll to the phone number and move your thumb over to the green call key. Or you scroll to the number, select “options” to bring up the menu, scroll and click “Voicecall” from the menu. Direct manipulation is very powerful and probably the primary reason that people find the iPhone easy to use.

The iPhone has a limited number of initial gestures. Gestures have to be system wide. You can’t add gestures for individual features. New gestures are comparatively hard to teach users and you are probably going to need redundancy.

There is nothing magic about the iPhone ease of use. Reduce the number of functions until they all fit onto the screen and let people interact directly with them. Apple deserves kudos for having the skills to do it, and the guts, stamina and balls to see it thru. Congratulation Apple, you have changed the mobile phone industry.

https://sender11.typepad.com/sender11/2007/07/the-ui-differen.html