by Will Eisner
Along with Understanding Comics, this is the most referenced book that examines the techniques that make comics a unique medium. This book takes a much more academic approach, making it a much less fun read, although it does provide some insights not found in Understanding Comics.
A lot of the text contained in the book seems to be striving for an academic sound, although sometimes it seems to take things a bit too far. Chapter three opens with this gem: "The phenomenon of duration and experience - commonly referred to as 'time' - is a dimension integral to sequential art." It reads like a textbook, but I think it does that because it tries to overcomplicate things in an attempt to try to gain more respect. I don't think this is really necessary.
The other unfortunate aspect to the book is that it almost entirely relies on samples from Mr. Eisner's own work to illustrate the points being made. Now, it certainly is a testament to his work that he has so many good examples to use, but it confuses the focus of the book from an academic analysis to a "behind the scenes" explanation of his own work. It also weakens the universality of the argument - do we really know if these things apply to the entire medium if we are only looking at one author's work? Obviously you can make that argument if you understand the historic significance of his work, but this book by itself can't make that case.
The three best chapters are those on imagery, timing, and the frame. These really get at the heart of what makes comics a unique medium by examining how the pace of the story is created, what control the artist has and what is expected of the reader. Lengthy multi-page examples then show the ideas in the context of a complete story, which is a wonderful way to see the techniques in action.
The other chapters seem less important, or easily summarized (The chapter entitled "The Application of Sequential Art"? Stories or instructional material. There, I saved you 8 pages and a strained attempt to differentiate "entertainment comics" from "graphic novels".) I have no idea the point of the final chapter, "Teaching/Learning Sequential Art for Comics in the Print and Computer Era". This talks a little about printing techniques but probably won't be informative for a novice or an expert, and the page on electronic comics isn't too shocking - "Regardless of the method of delivery the fundamentals of sequential art remain the same." Of course, he names for elements that were not discussed as such elsewhere in the book.
Overall, I would recommend reading the three chapters on Imagery, Timing, and The Frame. Be prepared for some overcooked text, but remember that this is a real comics pioneer revealing hard-earned knowledge, and it is worthwhile to pay attention. But I would start out with Understanding Comics first, which does a little better job introducing and explaining some similar concepts.