I have it, and I think it's worth reading. The English is not great, especially in the first edition (I heard some improvements were made before the second edition, which I think is the one I have).
Mr. Chan is a perfectionist, and has strong opinions, but as long as you're willing to read his opinions and be willing to form your own (keeping in mind that his opinions are probably more informed than yours or some random guy on the internet like me), I think it's a good read. Also, keep in mind that Wu Shing (the publisher of this book, Art of Tea Magazine, Puerh Teapot Magazine, etc.) and their authors have been accused by some of promoting certain cakes to increase the value of their own holdings / collections (for example, they have a close relationship with Changtai, and a lot of Changtai cakes get championed in the books and magazines). I'm not personally in a good position to judge the veracity of these accusations... just putting it out there. Rumor or not, it's worth bearing in mind, at least if you're using their books / magazines to base your purchasing decisions on.