I know that he has a cult following, but I have found his work to be shallow and not particularly thoughtful.

Amen. Gaiman's primary strength as a writer is that he has a pretty good ear for dialogue. Given the arenas in which he customarily works (comics and then fantasy), I think that's given people an inflated opinion of his skills. His plots are frequently murky and deliberately anti-climactic, with a Chris Claremont-like reliance on ominous allusion and portent that isn't always paid off. There's also a preciousness and a tendency to pander to a perceived audience that sticks in my craw.