I still argue that Sara Shepard is practically her own genre among YA books, and I'm okay with that. This book very much fits into that genre.
We're looking at a thriller, certainly, and there is some murder and some mayhem and a lot of unanswered questions, many of which are still unanswered at the end of the book. That's kind of Sara Shepard's forte--series that somehow feel like Soap (anyone else remember that?) where the questions that come up get answered only to be replaced by more and more questions as time goes on so the hook is never really lost. You always want to tune back in to see (or read, in this case) more.
I had a minor issue where I went through the entire Pretty Little Liars series in about two weeks, which was vaguely horrifying and vaguely impressive. Although I've paused in this series, most of that was due to fear that I would do the same thing here. The novel is intriguing and fun, if you don't mind very fluffy soap opera-like reads.
The idea of twin sisters separated at birth has been done many times, certainly, but this puts a bit of a spin on it by having one of them dead, but still narrating.
The list of suspects would actually be a list of everyone in the entire novel, so I'll leave that part out. They're an intriguing bunch, though I don't think I like above half of them. That's okay--it makes it feel less problematic to assume they're all out to get the main characters.
I'll be picking up the rest of the series for sure at some point, but a lot of that is how compulsive these are. I need to see where things end up, and I kind of love the crazy detours and red herrings that it takes to get there.