Once I was able to get a sense of the rhythm in Jimmy Corrigan, I found the book to be incredibly engaging and compelling.
One series of panels that really caught my eye because of its visually complexity and, at the same time, because of its overall narrative clarity, was toward the end of the book. The two pages deconstruct the relationship between Amy's birth family and Jimmy's family over a series of generations. Amy's birth mother was a high school student who gave her up for adoption. Her mother's father was the son of the woman who was the illegitimate child of Jimmy's great-great grandfather. (I think I have the "greats" right, if not, I think you still get the point.)
Look at that last sentence- it is a mess. But illustrated and linked together across two pages, it is simple, articulate and elegant in the way that it teases out the relationship between these two people who, up until this point, had no relationship or connection at all (and who may not have any relationship with one another into the future).
The other element that these series of panels help to convey is the kinship or similarity that these two characters have emotionally in addition to their genetic relationship. Amy looking out into the hallway in the first frame, seems to make the point that she is, indeed, all alone. Jimmy throughout the story and especially in his empty rooms with high ceilings and bare furniture is also, all alone.
These panels also provide something of a revelation in the fact that the cantankerous grandfather, who has been so casually bigoted towards her, is actually Amy's great-uncle (I think that's right). These series of panels make the reader re-evaluate all of the relationships within the book (or at least it did for me). Amy becomes a pivotal, important figure. She's also the only female whose entire face is shown. As a character, she is one of the few who is actually sympathetic. Her one act of frustration/grief/cruelty towards Jimmy is entirely forgivable and understandable. The appearance of this man/child (Jimmy), who her father reached out to and who has a striking physical resemblence to the men in her family - has disrupted her life and, perhaps, made her feel like an outsider in her own family (especially since it is possible that she may have felt this way already, especially after her mother died).
Although her appearance in the book is relatively brief - it seems fitting that she is the character featured in the epilogue. As a character, she is one of the few in the book to which I feel I can relate to.