I used this book as part of my grad level LP course that covered the first half of the book. Let me start out by saying that this is by no means a beginner's book. This book assumes a strong Linear Algebra and basic OR (assumes you know the Simplex method solution procedure, etc.) knowledge.If you are looking to get these OR prerequisites, then refer to the basic OR books by Hillier & Lieberman, Wayne Winston, Ignizio & Cavalier or A. Ravindran; this book is not for you.
This book is outstanding for understanding the theory and mathematical mechanics of LP and the first half of the book covers this comprehensively. The excercises in this book are outstanding (and can be hard). For those who need this book but are weak or rusty on the basics (like I was :) ) refer to one of the books above (I liked the Ignizio & Cavalier book a lot). I can't comment on the Network flows part of the book but it will almost surely be excellent if it is anything like the first half.
An excellent book for the intended audience.