I think if The Merciless was like the last 20 or so pages, it would've really been a horror novel. I guess it really depends on what scares people though. It seemed to want to shock readers more than terrify them and it left me feeling a little disappointed. Yes, it was bloody and gory and cruel, but no it wasn't exactly scary or creepy.
The book introduces the characters in a somewhat rushed way, and I never really connected and got a feel for them before the real gore begins. That's mostly what it is. It's Mean Girls gone psycho killers and there are really so many similarities between the girls in The Merciless and the ones in Mean Girls that I snickered a few times while reading the first 200 or so pages of this book.
In the end, there's a twist that left me wondering...what the hell happened?