Simply put, Jimmy Corrigan is the pinnacle of what graphic novels are capable of as an art form- story, structure, graphics, everything. I’m ashamed to say that I’m very late in reading the book, so I’ll let you read proper reviews here:

Guardian

Flak Magazine

The Independent

I’ve heard some people say that the book is frustrating and difficult to read because of the nontraditional structure, but the structure is part of the meaning. It is not just a story with pictures, as many comics are. It is more than that, and I compare any difficulty in reading it to the difficulty of reading any quality literature (think Cormac McCarthy, Kurt Vonnegut, James Joyce, et cetera). Check it out here.

Some excerpts (these are random, except for the third and forth pages here, which are presented in order):