An interface has a beat, just like a song. It can be slow, fast, syncopated or straight time.
And mobile is a beat you can dance to. The taps on iOS leave so much room for animation and delight: layers and levels become successive opportunities for folding enchantment into experiences.
I have been thinking about this for a while. It came into focus on seeing Elvis Costello tonight. (I saw him the first time in college, again with Bob Dylan, and now with The Imposters.)
The blazing talent was always there, but the whole package is so much more awesome this century than the previous one.
The parts were all there before, just not as tightly polished and integrated.
Interfaces, too. Mobile interfaces are for dancing.