Watts explains Zen, to the extend that it can be explained, so that we can understand it, to the extend we should try to understand it. Though Zen is a branch of Buddhism, it responds to the formal ritual of its progeny with spontaneous thoughts and actions. The emptiness and silence of Zen contrast with our hectic everyday life amid rush hour traffic. The preoccupation of the self as the one to think and feel and to act and improve, and the desire for enlightenment all hinder our spiritual walk.
I particularly like the section on Zen and the arts. Zen has influenced artwork and poetry in China and Japan. Through Zen, we realize the white spaces in the paintings and the silence within the koans are as important as the brush strokes and the words. And cha-no-yu, or the tea ceremony, is as much a spiritual experience as an aesthetic one.
If you are curious about Zen, this is the book to start with. Zen 101 for beginners.