What is the author's tone in Understanding Comics by Scott McCloud?

Understanding Comics is written in a very subjective tone. Although McCloud vaguely considers the fact that some of his core beliefs may be inaccurate, he does not waver very much in his adherence to them. Occasionally, he opens some topics up for constructive debate, and indeed in closing the book, he pronounces his intent to stimulate debate, not settle it. Yet the reader is left with the impression that the author's mind is fairly made up on the issues being presented.