I enjoyed this book. I personally did not find it condescending. Additionally, the implementation of a Forth interpreter in this book is the best introduction to Forth I've seen (even after years spent playing with Forth and reading one or two books on Forth). But I don't recommend this book as an introduction to (Common) Lisp.

I recommend this order:

1. Practical Common Lisp

2. On Lisp (kind of a big jump, so maybe check out ANSI Common Lisp)

3. Let over Lambda

4. Lisp in Small Pieces (especially if you want to implement a Scheme or Common Lisp)

With Common Lisp the Language (Guy Steele) and ANSI Common Lisp (Paul Graham) somewhere in the mix.

These are all excellent books and must-reads for anyone interested in programming languages and/or the Lisp family.