I purchased this book after browsing around in a local store, and it turned out to be a great purchase. I'm a beginning gardener, and I wanted something that would not only explain the basics to me, but help me out with more advanced decisions.
The beginning is a breakdown of Sunset's climate zones, with wonderful maps showing just where you stand when it comes to the growing season. Then there is a section that helps you find a plant by certain categories such as fragrant blooms, decorative ivy, blossoms by season, and even such obscure classes as arid, windy, and humid climates.
The meat of the book consists of an encyclopedia of sorts, with hundreds of entries for different plants that grow in the west, complete with scientific names, growing habits, and helpful hints.
The last portion of the book is a quick reference for everything from watering styles to proper composting techniques.
I recommend this book to anyone, beginner to advanced.