The book wasn't that great either compared to Ellis' other novels that came after it. I haven't seen the film but given that I didn't really enjoy the novel, I wasn't goint to watch it anyway.
My first read from Ellis was The Rules of Attraction, which was made into a movie too. They also changed quite a bit as far as plot goes, but I found both of them amusing - the novel is a lot more depressing, though.
Also, Ellis is famous for being a bit of an asshole at times, so him bashing the adaptation in his next novel didn't surprise me much.
I haven't read anything from him since Lunar Park, which was entertaining and frightening, but maybe I should. It's been a while.
Good read, Paul.