This is a very simplistic rendition of the theory of the enneagram meant to be specifically for understanding children. If you're looking for simplicity you'll enjoy its brevity and the often humorous cartoon drawings of various "types" of kids and their responses to everyday situations throughout the book. If you have any knowledge of the enneagram already you're more likely to find it dull. There is very little detail, and the descriptions of types are rather perfunctory. There is no discussion of how a particular type of parent might interact with a particular type of child. Each type gets its own chapter with a ten question quiz suggesting whether or now your child might be this type, followed by several pages of illustrative cartoons, and then a few pages discussing the "common problems" of each child. The "problems" display the author's view of child raising: no. 1 is "getting to school on time", 2 is "study habits" and 3 is "manners". I would recommend getting a decent general book about the enneagram, and/or a decent parenting book instead.
I am a psychiatrist, but all of us who are trying to be good parents tend to try to treat our children like we wish we had been treated: in my case I have a natural tendency to try to provide my children with as many stimulating opportunities as possible. But I am a 7 in the Enneagram system and my children are not! So it is a constant reminder for me that my little 9 daughter would rather cuddle than go to theme parks, while my little 8 daughter wants more and more action! Elizaeth has written a fabulous, concise, book reminding us of the interactions between parents of one type and children of another. A book that is both essential and ahead of its time.