I liked American Gods because it shows Gaiman finally figuring out a narrative way to turn his dramatic weaknesses into strengths. A book in which all of the characters and plotting are flat one-dimensional cardboard archetypes because they're designed to be flat one-dimensional cardboard archetypes... ingenious! It's a much better system than Gaiman's usual writing, in which all the characters who are supposed to be "characters" still turn out to be made of flat cardboard and glued together with complete wastes of time. The trick all along was to stop trying for success and simply celebrate complete failure instead.
Note: when I say "liked" what I really mean is "found myself loathing it less virulently than usual."
A more fun exercise is Good Omens, in which Gaiman wrote half the characters, and Pratchett wrote the other half, and see if you can guess which are which. Hint: the ones based on Big Ideas are Gaiman, and the ones that have even the most token amount of depth are Pratchett.