Finished the book today. The beginning is slow (as for the four stars) but really starts picking up as you read on. I couldn't wait to figure out what it was that Cady was forgetting, and boy did I not expect it. It's just been stuck in my head, the fate of the poor, poor liars.
I definitely would say this is an older teen/adult book (I'm an eighth-grader and it was kind of scary), but totally worth the read. The suspense and the clues and everything fitting together at the end! Oh, just brilliant.