Moore's novel first came to my attention shortly before Jane Campion's feature-film was released in the fall of 2003. Back then I knew nothing about the author (who happens to be a fellow New Yorker, although she is originally from Hawaii), but I worshipped and revered Campion. I picked up In the Cut at the library one day, and finished it in less than five hours.
Moore is a serious writer who has a way with language; and the knockout ending is exactly that--I was left scratching my head for a few minutes, not sure of what really happened. If anything, read it for the last 4-5 pages!
That said, although Campion's film alters a lot, it is a beautiful adaptation nonetheless. Rent it if you have time.