This book essentially attempts to reproduce excerpts from the Mustard Seed Garden Manual of Painting, a classic instruction book on Chinese ink painting from the 17th Century. I got a lot out of Mai-mai Sze's contemporary analysis of the history and philosophy behind the book (and 17th Century Chinese culture in general) but couldn't get much out of the excerpts from the Manual itself. This isn't really Sze's fault--she acknowledges herself that parts of the Manual were written in a way to aid memorization that is completely impossible to effectively translate into English, it references artists and symbology that have been lost to history and, even worse, she was left having to work with reproductions of the original lithographs that completely lost the gradations of ink tones in the original edition of the Manual she was using (this problem may have been solved in a future edition of the book--the copy I was reading was a 1959 printing.)
The text is a very useful introduction to those with little knowledge of the traditions and history of Chinese brush art. My edition (bought in the 70s and now falling to pieces) is let down by the stark, high contrast illustrations (i.e. lacking gradation and even details). Still a worthwhile buy and at the time, almost on its own as work of accessible scholarship in English.