I kept going back and forth between 4 stars or 3 stars, because I'd really rather give it 3.5 honestly. But, I'll stick with 3 so I remember. 
 I want to start by saying I had extremely high expectations of this book. Everyone kept comparing it to The Night Circus and it's been rated pretty high by a lot of other YA readers I know, so I'm not sure if my high expectations were just way too high, you know? 
 Anyway, I was mildly disappointed by this book. It was magical, yes, but the two sisters were just not people I feel like I got to truly know. Tella seemed to be more of a plot-device than a real person, and I don't feel like the eventual twist made sense with her personality as we knew it. It's believable, and yes Scarlett's own view of her sister is a little unreliable it seems, but I feel like it was just too convenient of a twist for the sake of the story. Scarlett, on the other hand, we get to know a bit, but she still never really jumps off the page at you. There was only one moment the entire book when I was like "YAAASS YOU GO GIRL!" And I really wanted there to be more of that later on. Scarlett is supposed to be super skeptical and not trusting, yet she trusts almost everyone she comes across, even though it literally never works out in her favor. The characters didn't seem to really have a solid characterization to them, which made it hard to get into the story and I caught myself skimming some passages as a result (I stopped and forced myself to go back and read them but still). 
 The setting was really the magical part of the story. There were moments that were really gorgeous and you really felt like you were there at times. I think the part that got me sucked in the most was in the Castillo Maldito. It was wonderfully rendered in the book. 
 Something that was a bit distracting to me was Scarlett's synesthesia. The way she sees colors and smells things around certain emotions or feelings or people. It was honestly just distracting and didn't seem to serve a purpose except for during the scene when she is looking for that one clue. I felt like it was just an overused thing that the author almost used as a crutch for showing vs. telling. It just seemed contrived to me, which was disappointing. 
 The book was a quick read, I finished in a day, so if you're looking for something pleasant and not a difficult read then I'd definitely go ahead and give this a shot. I will say, that I enjoyed it enough that I'll definitely read the next one (especially since it ends on a MAJOR cliffhanger and I cannot abide not knowing what happens next). 
 And while we're on that topic, there is a huge cliffhanger at the end. I'm not going to spoil it more than that. I'm only even bringing it up because I know some people (me) hate cliffhangers and would rather wait until the whole series comes out before they get stuck on one. I didn't even know this was going to be a series, I thought it was a standalone and was mildy furious to find out I have to wait until who knows when to find out what happens next. 
 I feel like this review sounds really negative. I didn't mean it to be! The book was pleasant and I did like it. I just didn't love it as much as I wanted to. I definitely recommend it if you're looking for an easy, pretty read.