The purpose of this book is to teach the skills required to design and implement programming languages. Design is an important topic for all computer science students regardless of whether or not they will ever have to create a programming language. The user who understands the motivation for various language facilities will be able to use them more intelligently.
This isn't a "how to" book; and, it certainly isn't a "learn XYZ in 21 days" book. It is the best book I've ever read about the design of computer programming languages. The author shows that there are common principles behind the design of various programming languages.
The languages covered are old: a machine-like language, Fortran, Algol, Pascal, ADA, LISP, SmallTalk and Prolog. However, this does not detract from the value of the book. Indeed it adds some interesting historical insight.
Don't go out and get it today, but get it some day...and take your time to read it through. Even if you do not agree with all the principles, you'll find a fascinating author who looks at real examples, draws out the motivations behind specific language-design, and threads them together to formulate broader, more universal principles.