It is actually a really good book. It explains the theory behind Zentangle, how it came about, why it is good for you and how to do it. It clearly shows how to do each design from start to finish, bit by bit. Once you have mastered each design, then off you go with creating your own Zentangle art. For someone, like myself, who can not draw at all, I found this amazingly brilliant. By breaking it down and showing you step by step how to draw the designs it has helped me learn to draw, something I never thought I would be able to do, so that is a bonus as far as I am concerned.
Zentangle is a brilliant way of "shutting out" the outside world. Because you are so focused on what you are doing it actually does calm the mind and puts you into a "Zen". I found it incredibly helpful to take my mind off other things and when you have finished you really do feel calmer - I can see the benefits and understand why this is being used by professionals to help people in therapy.
This is a starter book and shows you how to create 101 tangle patterns, which is a huge amount to get you going. I have had this book for a while and have not gone through all the patterns yet, but have already created some lovely work and have even done some more advanced work, where I have used the patterns to infill an outline of a plane for a Father's day card. The possibilities are endless. I do recommend that you use the pens suggested for your artwork, but when you are practicing the designs, then use a basic art book and/or graph paper and any fine nibbed pen.