I have to admit that after after seeing an endless amount of Vampires, Werewolves, Fae, and other mythical creatures that it was nice to see something that I'm familiar with but not overly exposed to.
Raise your hand if you remember The Odyssey. If you never read the Odyssey and are over the age of 15, I'm pretty sure that you don't live Earth. But in any case, for those of you who don't know what a Siren is, it's a mythological creature in the form of a beautiful woman that lives in the ocean and lures men to their deaths (enter evil woman laugh here). In Homer's The Odyssey, Odysseus has his men tied down so that they don't go jumping off the ship toward these crazy ladies.
But while the story did have to do with Sirens, it was also a book about teenage girls finding out who they are. Both Justine and Vanessa come to terms with who they are and who they want to be/where they want to go in life. I think this is a good theme given the intended audience of this book. Justine isn't quite sure where she wants to go to college and feels the parental pressure of choosing Ivy League and Vanessa, I think, is trying to get out of her older sister's shadow and come into her own. This story could also been seen as focusing on the different types of relationships between siblings. Not only sisters - Justine and Vanessa, Paige and Zara, Siren Sisters - but also the bond between brothers - Simon and Caleb.
My one pet peeve is that it's really hard for me to imagine anyone's parents letting their 17 year old daughter drive unaccompanied to their beach house to "figure things out". Especially when their older daughter's body was just found on the shore of the beach town. Really? I'm sorry, this would just not happen in real life. But then again, I think this is more plausible than Sirens. :)
Overall, Vanessa was a likable character that I could see myself being friends with. :)