The subtitle bills this as a "mystical thriller". Sorry, there was nothing terribly thrilling about this, and I have no idea why the author would have called this a thriller. Mystical? Sure, maybe, depending on your interpretation.
Chelsea and Miya are separated by thousands of miles and a mutual inability to reach out to each other. But despite never actually speaking to each other, they feel connected through their blogs. (Which sound a lot like tumblr blogs, pictures with a line or two to go with them.) There are a lot of similarities and connections between the two girls, and more so as the story goes along.
It was a very quick read, even though the lack of capitalization slowed me down. Although I could identify with the girls, to a certain extent (liking being online, but being too shy to comment) I still didn't get involved in their stories. Maybe partly because they felt detached from their own lives. I get that, but it does make it harder for me to connect. I could also see where this book was heading from very early on, so there were no surprises.
I can see this appealing to teens who are interested in the gothic lolita style, though the style itself didn't have much to do with the book. I got the feeling that it was just window dressing, because any other style or no style at all would have suited just as well.