Since you've made it this far, allow me to briefly write about the book--the other commenter puts Glaser's personality so well in context. The book's content is graphic material, both published and rejected, complemented by Glaser's succinct explanations concerning any of the following: historic/social context, guiding professional principles, technique and process, interpretation, the tension between client and creator, etc. The text and the graphical works are very diverse, ranging from terse to lengthy, and simple to complex, respectively. All in all, the feeling of being in Glaser's presence (in class or studio) is likely to grow in you as you progress through the book.
If what you've read so far compels you to get the book, do so by all means, it's a 5-star! Otherwise, if, let's say, you are looking for for something akin to a cafe-table book, this one gets only 3 to 4 stars.