But trust me, this book is one I'm very glad to have read. More importantly, glad to have read first. It's a list of no-nonsense principals which teach you the basics in an easy-to-understand manner. I really can't recommend this highly enough, cover or no.
Note that the book I linked to is the wrong one. One of the comments has the correct book.
Also note, this book doesn't talk about color, but only the other basics.
This seems like a dichotomy but its not. The reason the cover sucks is that Williams is not naturally good at design. This means for her to get good at it she had to actually learn and understand it. This is why this book is so good. However, she never learned how to design with color. Most of the designs she makes using color I feel are bad.
That said this book ROCKS, is hands down the best book when it comes to design basics of: Proximity
Alignment
Repetition
Contrast
Typography