Adam Goldstein wrote his first book at 16, and has written and edited a number since then. He is president emeritus of the MIT Debate Team, and the CTO of BookTour."
Overall, it's not bad. I'm wishing I had a copy of a book I had some time ago, Tao of Applescript which was much better than this one. It's okay, but the quality compared to other learn a programming language books (e.g., O'Reilly's Learning X books) is lacking.
In addition, this book now is fairly old. It was originally published many versions of OS X ago. So, there are things that aren't covered.
I'd recommend looking at a different book, like AppleScript 1-2-3 which while I haven't read it, I've heard many recommendations for it from people I trust.
This one almost earns its title... When I think "manual", I think of a comprehensive glossary of keywords, expressions, functions, syntax, etc. This book does not really have that; instead, it leans on that weaksauce crutch of "but AppleScript is just ... like ... you know ... English!" If you read it cover to cover and work through the examples and use-cases, you'll pick up enough of the AppleScript to get by. I recommend keeping your copy of VoodooPad open at all times while reading this one though and taking notes on syntax etc. You'll thank yourself later.