I don't remember having any issues with the ending of "Good Omens". Maybe it's Pratchett's influence, or maybe Gaiman's just spotty in that respect. It's not something I've noticed with his short stories at all; perhaps it's a natural problem for someone who is transitioning from shorter pieces (short stories, comic book episodes) to novel-length work.

Gaiman is one of my favorite writers and one of the only people I will consider buying in hardback. (I only held off on Anansi Boys because I had been a little disappointed by American Gods.)