Understanding the Kings Indian is a wonderful book. It is designed for midlevel players looking to expand their repertoire. The book starts gently and eases the player through the different nuances of the opening.
The book is more interested in establishing firmly an understanding of the opening where it is going and what it is trying to accomplish than in deep analysis of lines.
For a club player this is a valuable resource but at the highest levels of play where only the latest and most timely lines are adequate this book will not do. This book is not designed to do that; it is a teaching aid in learning why and how of an opening and it does it extremely well.
Some of the best advice on chess books is which ones not to buy. Some Great players are poor authors and can't put what they do in an understandable format for a book. This book avoids that problem and is detailed, organized, useful and easy to understand.
1 Do I like the book? YES!!!
2 Would I buy this book again? YES!!!
3 Do I recommend this book to others to buy? Yes.
Do I use the Kings Indian in my personal play? No. I just don't happen to like the type of game it gives me but if you play it against me I am ready! I still recommend this book highly; you might like the KI where it just isn't to my tastes.
There were only a few books in the "Understanding The____" series and I own and recommend them all especially "Understanding The Open Games."