In mentally listing all the ways this book (well, the chapters I read, at least, for class--4 and 5) fails, I realized that it doesn't, totally. All the ways in which Lester royally fails at expository writing in chapter 4 are the exact same ways he succeeds (for the most part) in chapter 5.
Reading this has made me rethink my own always-interdisciplinary approach to stuff, because clearly it's hard to do well. In chapter 4, Lester first confused me because he said that the primary colors were red, blue, and green, and I know that to be totally incorrect--then, after checking with my art teacher mother, and continuing to read, I realized he was talking about the primary colors of light, which are different from the primary colors of pigment. Problem solved, except throughout the chapter he keeps using theories and vocabulary from art/aesthetic theory and practice and mixes them in with neuroscience talk and color/light spectrum stuff without ever being clear on what he's referring to, and it's a big ol' mess. I know just enough about two of the three of those things above to have a flickering lightbulb of "Wait? Huh? Is he sure about that?" every time, so it made for really obnoxious reading on an already physically obnoxious low-quality PDF.
In chapter 5, though, he does a better job of incorporating a great amount of disciplines and theoretical schools and uses them to illuminate, inform, and expand his scientific points, rather than obfuscate them. I was right along for the ride with Barthes, de Saussure, psychology, linguistics, advertising. Aside from some bad metaphors and examples (we can't be experts in all fields, after all), he really did a good job of connecting and/or comparing his topic to ones that various types of readers would be more familiar with. More science writers should strive for chapter 5 style, but NOT chapter 4.