I liked being kept in the dark at the beginning of the book, but the twist made me stop in my tracks - at first I thought the author was pulling the Girl on the Train move, giving information that was left out to serve as a twist while actually just being a cheap ploy. However, I went back and realized the author just let me assume things, which was more satisfying. It still took me out of the book a bit, but the ending wrapped it up pretty nicely.