The book came out back in 1990. I stumbled on it at a book wholesaler and decided to take a look. I'd read and enjoyed books by Gaiman (American Gods and Neverwhere) and had heard of Pratchett (I may have read some of his stuff; I have a leaky memory for light novels), so why not?
I have also found word that Good Omens is a movie project, if on hold, for Terry Gilliam, the Monty Python alumnus and director of Time Bandits and Brazil (two of my movie favorites). I like what Gilliam had to say in an interview with SCI FI Wire about why the Good Omens movie has been hard to get financing for:
"Unfortunately, I think our timing was rather bad, because we turned up in Hollywood in November of 2001 talking about a comedy film about the apocalypse. That was just bad timing."
No doubt. Still, I hope the film gets made. There's not enough of this sort of silliness around. I think silliness might be a help, or at least a relief, right now.