The reason why the iPhone is a mass success and the N900 is not (yet maybe?) is because Mr. Jobs is like me: a ruthless critic. He goes hard on his developers and engineers and nags them until they get things done right. Less functionality let them focus on fewer things and they can polish it to the ultimate usability. It also means less features to support. He is unforgiving when it comes to the user experience. No exception. If something takes an extra click to accomplish, it must be simplified. That's why the iPhone just works.