This is my personal experience about book- When to go for this book - if you are totally new to C language, there is no concept or knowledge of programming or want to develop ur logical programming skill then go for this book.
Currently I am using 12th edition of this book. The author provide the book in so simple language that every person who really wants to learn "C" can easily learn while going though it. Explanation for any concept in this book is very easy to understand.
One most important thing about this book is the concept of basic things which is most important things to learn any programming language, the author of this book explains basic programming concepts so clearly or in detail so that you started with "C" programming.