Matt Gemmell – iPad Application Design:

"Most users need only a small set of features, and software is better when it’s focused. A nice side-effect of focused software is that the UI is easier to design and comprehend (because there’s less of it, and it’s more obvious why each thing is there). The trick is to figure out which small set of features are actually important, and implement only those.

[…] Be focused, targeted and comprehensible. You can add things later when it becomes clear what’s important, but you’ll never recover from a confusing first impression."