In announcing the Apple Watch, Apple says that it has deliberately created a new user interface to create the best user experience on your wrist. Shrinking down iOS to fit in a small square screen was not optimal since the display is too small, so Apple went ahead and created a new way for you to interact with your wrist.
"The display also senses force, quite literally adding a new dimension to the user interface," Apple designer Jony Ive said. "We're now at a compelling beginning — designing technology to be worn, to be truly personal."
In its design consideration, Apple merged the the digital with the analog. There is a digital crown on the side of the watch and infrared LEDs and diodes helps to translate rotary motion and navigate the UI. The Apple Watch will allow users to zoom in and out and scroll through lists without blocking the screen through the digital crown. The watch could sense touch and force and could recognize between a tap and a press. There is a taptic engine that is used for haptic feedback.
Interaction with the watch could also be done via voice through dictation.
The watch will sense when you're raising your watch, perhaps to check on the time or notifications, to turn on the display.
A new interaction called Glances will allow you to swipe through information efficiently.
A button below the crown goes directly to friends.
The watch itself is powered by a new Apple S1 processor.