I use this book when I teach design process in graphic design. It's a great book for generating ads and ideas. Granted, it's 25 years old; however, Photoshop enhances but does replace a good idea. Garchik lays out his process with no-nonsense clarity. Everyone I have taught his technique understands it. It's also great for getting a linear thinker to generate creative ideas. It contains good (albeit slightly dated) images that support his healthy amount of approaches to generate advertisements. Plus, you can pick up a hardcover cheap!
I purchased this book in NYC as a university student and have used it for reference my entire career as a news artist and writer for daily news and monthly magazine production. It is an excellent, fast, helpful tool for any artist under pressure to create an original idea NOW! This book is perfect for the creative artist especially during difficult times: at work sick and exhausted and must produce an original idea on strict deadlines.
A useful reference for idea generation, the author assumes the reader already understand design and offers a system for design thinking. It's not a how-to-design book but a how-to-think book.