While the writing and the pace of the book make you want to keep reading until you are done with it, the excitement about the premise of the book fades towards the end. There are no consequences - worse, there are no stakes. It also fed of tropes with no effort to disrupt any of them - the pretty, bratty sister; the ugly older sister who cares for everyone like a modern-day Cinderella; the monstrous father; the incapable mother; the shallow, shallow men... 
While it was a fun, quick read, it felt flat. Also, as a lot of people have pointed out, it's absolutely not a thriller.