I'm a librarian who loves anime, manga, and reading a wide variety of genres.
Zelda's a better, more fleshed out character here than in the movie. In the book she actually has a dream for her future: she wants to own her own cleaning business. Lainie, Strickland's wife, is also a much better character here than in the movie, although in her case it feels unnecessary - unless the story is tweaked so that she has a larger part, she really doesn't have anything to do with the River God storyline.
And yay, the whole "I only wash my hands before using the urinal, not after" conversation doesn't exist here. Will the rotting fingers be edited out too? I doubt it, but I can always hope.