I found Norman's writing exciting and it made me think about things I've always taken for granted, and never really gave a second thought. I never realized how many interfaces we interact with in our daily lives. And I never considered the designers, and the difficulty balancing function and ease of use. The best designs are those with a very natural learning curve, that are simple, intuitive, and straightforward, like a lightswitch. On the other hand, interfaces sometimes need to control complex tasks, like washing laundry, and simplifying them creates confusion. But as long as everything in a complex interface has a clear function, it can be understood. I don't have to think much about the controls in a car, because they are clearly labeled and easily within reach.
The most important aspect of an interface is feedback, so the user has direct response for their actions. Audio and visual cues are very important. Feedback should have a clear relationship to the action being performed, such as a phone beeping in increasing loudness as the volume is turned up. Something that frustrates me a lot is inverted controls, where an action produces the opposite result. An example would be in a flight simulator game, where a push of the joystick makes the plane go in the opposite direction. Games often have an option to invert the controls, and some people prefer them that way, but I can't imagine why. It requires that you form a new conceptual map and ignore what your instincts tell you.