To me, the only novel of his that works well is Neverwhere and that, incidentally, was first written with visual representation — a tv series — in mind. Good Omens I guess was fun, but really seemed more a Terry Pratchett novel, Stardust is kind of boring, and Anansi Boys wrings a disappointingly shallow story from a great basic metaphor of identity.

American Gods is in some ways more ambitious, but it also seems to me directionless, as if Gaiman was working on the strength of a clever idea, but never quite figured out where to take it, resulting in a rather weak last third.