Cheng Yan is a talented Chinese brush painter, offering a text which presents a cross-section of traditional Chinese brush painting techniques.
Please note that traditional Chinese brush painting, the ancestor of Japanese Sumi-e/Sumi painting, is different from Sumi painting, and may present imagery and technique which practitioners of strictly Zen painting may not find as useful as books relating strictly to Japanese styles.
Cheng Yan is a brilliant painter, but I find that his text is more suited to artists who are already very familiar with Chinese painting techniques. This book walks you through several styles of composition, but there is much that is assumed by the author. He expects you to already know many techniques and styles of brush work.
He does show several types of brush strokes in one of the introductory chapters, but if you're looking for a book that will teach you to do Chinese brush painting from the ground up, I would recommend Jane Evans or one of many published in China.
I do use this book frequently as a personal reference book while painting. I am also inspired by his beautiful, xieyi style (freestyle) painting.
I would not recommend this book to absolute beginners, but if you've already mastered the Four Gentlemen, or if you've been doing Chinese brush painting for a while, this is a great book to keep on your shelf. I am giving this book three stars because I feel it has been marketed as a beginner's book, when I would really recommend it as an intermediate book.