This book doesn't help to get systematic, general, and consistent knowledge about how to design a new programming language or how to develop a new compiler. Authors tend to explain even the most simple things using a lot of words, making an illusion it's a complicated stuff.
After reading first chapters of this book, I have decided to stop and to search for another sources of explanation, and I found one very helpful, useful book "Engineering a Compiler" by Keith D. Cooper and Linda Torcson. Some passages below should give you a feeling of how different they are.
On Context-Free Grammars
1) from "Compilers. Principles, Techniques, and Tools":
[...]In this section, we introduce a notation - the "context-free grammar", or "grammar" for short - that is used to specify the syntax of a language. Grammars will be used throughout this book to organize compiler front ends.[...]
2) from "Engineering a Compiler":
[...]The traditional notation for expressing syntax is a grammar - a collection of
rules that define, mathematically, when a string of symbols is actually a sentence
in the language.
Computer scientists usually describe the syntactic structure of a language
using an abstraction called a context-free grammar (cfg). [...]