I finished American Gods fairly recently.
It's funny, but 'meh' was precisely my reaction. There were a few nicely-written and fairly clever sections, but it didn't really hang together as a novel.
I thought there was at least going to be some kind of comment on the conflict between the old world gods and the modern ones, and whether they can co-exist in the modern world.
The quality of character-depiction is mostly at cardboard-cutout level, and certainly never rises above cliche.
I really did like Sandman and Coraline, but Gaiman is only at his best when the medium allows him to be fragmentary and anecdotal.