This book is intended for anybody who needs to build or maintain a large-scale network. It is not a theoretical book for classroom use, and it isn't intended to help programmers with designing applications. Instead it is a hands-on set of rules, guiding principles, and useful tips for people who build networks.
So it should be useful for network-operations people who need to understand the overall logic of their network. It should also be helpful to engineers who need to think about upgrading parts of an existing network in a logical way. And it is particularly relevant for network designers and architects.
In short, this is the book that I always wanted to read when I was starting to work on large networks.