Dan Simmons is a really great writer. I've read only three novels by him and they are some of the best in the genre i've ever read:
Carrion Comfort (Horror)
Hyperion & Fall of Hyperion (Science Fiction)
I have to say...Carrion Comfort was really good. The character of Melanie Fuller...Yikes! Damn, she scared the shit out of me. I never thought I'd be frightened by what an old woman might say or do, nor would have considered an old woman to be one of the most terrifying villains in modern fiction.