I strongly agree and I can't recommend it enough. It's not a good first book, though - it's not meant as an introduction to Common Lisp (for that it, in fact, recommends Practical Common Lisp). It's best read if you can already find your way around Common Lisp REPL, and write some basic programs - it systematizes the knowledge, explores various quirks of the language, and shows you practical solutions to common problems.

As for introduction, another nice book is Land of Lisp - it introduces you to most of Common Lisp by means of writing games of increasing complexity.