I finished reading Jimmy Corrigan. My friend Greg loaned me his copy. What an amazing book. I've really been spoiled reading Blankets and Jimmy Corrigan within two weeks of each other. (And having read Maus a month earlier) I'm trying to think of anything else significant I have yet to read. For the most part, I've hit all the touchstones of our beloved medium.
Jimmy Corrigan takes all the possibilities for the comic book medium and pushes it to its maximum potential. I believe the highest compliment you could give a comic book creator is to say their work could only be told within this medium. Jimmy Corrigan is so perfectly set within the world of text and image, to attempt it in any other narrative medium would only diminish it's scope.