This is not a traditional reference book or a `How to' guide.
What it is, is a very enlightening overview of the whole design process, where the author shares his experiences in a lighthearted yet informative manner. Know Your Onions: Graphic Design
covers all the disciplines that the modern designer now has to deal with on a daily basis, breaking them down into small bite-sized sections, before finishing each chapter with a useful recap.
As an old design dog myself, I didn't (want to) believe that I could be taught any new tricks... how wrong I was. This book has enabled me to step back and look at my own design processes, eliminate some of my bad habits, discover new time saving tips and increase my knowledge, especially with regard to typography.
I would recommend this book to anybody who is serious about becoming a better designer or if you are taking your first steps into the design industry, it should form an essential part of your toolkit.