I wouldn't say that book is very good at all as a learning book. It very loosely touches upon each of the basics, with just the basest of each fundamental. Most of it is just pages of finished artwork by various artists/illustrators to serve as inspiration, so if you want that, go ahead. You should go Robertson, or something more specific like the books you'll find through the sticky, if you actually want to learn things proper.

There's a good segment about how to find the golden ratio on your page, regardless of proportions, for compositionl purposes, but you can find that info online I'm sure, and it's not the first thing you should learn when "getting good".