In my opinion, no single design is apt to be optimal for everyone.

No product is an island. A product is more than the product. It is a cohesive, integrated set of experiences. Think through all of the stages of a product or service - from initial intentions through final reflections, from first usage to help, service, and maintenance. Make them all work together seamlessly. That's systems thinking.

If you think of the product as a service, then the separate parts make no sense - the point of a product is to offer great experiences to its owner, which means that it offers a service. And that experience, that service, comprises the totality of its parts: The whole is indeed made up of all of the parts. The real value of a product consists of far more than the product's components.

What makes something simple or complex? It's not the number of dials or controls or how many features it has: It is whether the person using the device has a good conceptual model of how it operates.

How do you discover a need that nobody yet knows about? This is where the product breakthroughs come through.

When you have trouble with things—whether it's figuring out whether to push or pull a door or the arbitrary vagaries of the modern computer and electronics industries—it's not your fault. Don't blame yourself: blame the designer.

We delude ourselves if we believe that skilled behavior is easy, that it can come about without effort. We forget the years of tuning, of learning and practice it takes to be skilled at even the most fundamental of human activities: eating, walking, talking, reading, and writing. It is tempting to want instant gratification - immediate expert performance and experiential pleasure - but the truth is that this primarily occurs only after considerable amounts of accretion and tuning.