When they say this book takes a visual approach, they mean it. This book is image heavy, which in my mind is a big yay. I've seen some art reference / tutorial type of books that are 90% text and that just annoys me. If ever there is a subject where you want more images to help you out, it's art reference. In fact the only reason I can't give this 5 stars is because the book seems to have taken the visual approach to the other extreme, giving a few lines of explanations of what can be complicated layouts. I'm all for dumbing things down (yes please!) but in trying to shorten things down so much, some things actually end up sounding maybe even more complicated than they are and then while you're sitting there scratching your head over what in the heck they're saying, well, it's sort of like did you get that, let's move on to the next part. That, however, is where the visual aspect saves it. The Appendix especially, which has no text, is very useful showing a image breakdown (usually 4 or more "step by step" examples of a picture as it is being drawn).
For people, like me, who find that perception is the greatest enemy when drawing, this is a useful tool. Not quite perfect but definitely a good starting point.