The purpose of this book is to provide a quick introduction to Common Lisp and then provide the user with many fun and useful examples for using Common Lisp.
Short, sharp, precise, pragmatic -- it is not SICP, nor it is "Practical Common Lisp" (both books are not without their merits, but they do not fit the bill).
This is a hacker's introduction to CL, getting you from 0 to 100 in less than 3 seconds. No endless musings of virtues of tail recursion and immutability, just a jet-fast overview of language features for those who already have 3-4 other languages in the belt (as most of us do, before trying to approach Common Lisp).
"Here's how we do arithmetic. List manipulation. Strings. Basic data structures. Want mutability? Mutable variables are defined like this. Global variables are here. Here's your first macro. Some I/O. Networking. Package system. OO stuff." -- this is about 50 pages, believe it or not.
"Let's play with some cool kid's libraries. How about full-text search and NLP? Here's how to load the library. Here are a few examples. Documentation is there. You can ask for advice here. Now go code and sin no more".
I wish other programming books were written like this.