I read a bunch of graphic novels this year, so when I saw this recommended in Steal Like an Artist: 10 Things Nobody Told You About Being Creative, I decided to check it out. It explores elements of comics that I'd never considered, like the reader's participation in filling in what happens between panels, the control of mood and pacing through panel size/progression, and the approaches to balancing detail in character and background art. There were a few sections I found a bit tedious, but most of it was quite elegant. Certainly a must-read if you're interested in the medium.