Although I've enjoyed most of his other work, I found myself growing frustrated while I read Dan Simmons's 800-page monster of a psychic vampire book, Carrion Comfort.
The problem? The plot is simply too repetitive. There are too many chase scenes and unnecessary reversals. (This is an occasional flaw of Tom Clancy's longer novels.)
In the introduction to the book, Simmons explains his own frustration with an editor who wanted him to either pare down the book, or restructure it to make it tighter.