Well, I knew when I picked this book up from the floor in my office that I'd read it before. But I sadly never remembered the ending til I'd read it all the way through...again. And I don't think it made much more of an impression the second time.
I read my list of categories several times, and can't even find one (not used already) that this book would fit. You've Been Warned by James Patterson & Howard Roughan was a decent read as a psychological thriller, but I really ended up reading it just to finish the ending. I will be sure to give it away before I accidentally read it again ;)