Simplicity is the ultimate sophistication.

Steve Jobs in Steve Jobs, page 127:

The main thing in our design is that we have to make things intuitively obvious.

When the original iPhone got in the hands of everyone one of the first thoughts were, “I can’t believe no one has ever thought of this before.” Simplicity is hard but when you really get there you also get to intuitive. A lot of folks had thought of something like the iPhone, but only one had the balls to make it.