UI is more than GUI. This interesting article talks about the interface of profucts and how it can be further developed in a correct way. We, as humans, like magic and visual experience (usually given by screens) but at the same time we want the simple and clear interaction of a knob (and in general a physisical movable element). The result is that the potential effective interactive interface is a mix between the two worlds.
Arthur C Clarke, ‘’Any sufficiently advanced technology is indistinguishable from magic’ and we love a bit of magic don’t we?”