3 stars.

What I Liked
The characters were great. They were multi-dimensional, each having their own goals and their own flaws. And they were willing to lie to reach those goals. There were so many twists and turns, trying to figure out what is true and who the good guys are, if anyone can really be said to be the good guy. I loved trying to solved the mystery of what was really going on.

What I Didn't Like
This is a very short book, only 220 pages, that would have made a great 300-400 page book. There's so much history that's not told and so many plot points that are just left behind. My biggest problem with this book, and the reason I'm only giving it three stars, is that the characters would often behave in unpredictable ways. They would be shocked by some event only to forget about it afterwards. A character would do something very clearly suspicious and no one would bother to investigate. The plans would not be fully explained: El would need to accomplish something that, as far as a reader could tell, was not in any way necessary for the plan. I can't be more specific without spoilers, so read at your own risk:

<spoiler>
El has known Anna for a total of 24 hours and yet she seems to know everything about her. Oh, she probably picked out these teacups, she would probably like this dress, etc. You met her 24 hours ago and have had three conversations total, most of which were one word answers on Anna's part. Where is all this insight coming from?
El sees some of the rebels forcing a human to mutilate his own hand. She questions Dan about it who claims that there are extremists in the organization. And then El just drops it. No questions about how many of them are extremists, what the extremists what. No doubt about joining an organization that openly claims to have members that like torturing humans.
El is saved by the rebels and yet shows up to the tournament despite never being told where it is. And no one questions this! No one wonders how she knew where it was, how she got there. No one questions her on where the rebels are who she has clearly spent the past week with. No one tries to get their plan out of here because clearly they arranged for her to be there. They just let her compete without any suspicion at all.
sWhen she's sent to the tournament, she states that she has to make it to the final round in order to save her grandma and for the rebel's attack to succeed. But why? What does where she places in the tournament have to do with anything? Why does it matter if she's the one who's currently battling when the rebels attack? It just doesn't.
Why does Cam, who isn't a part of the rebel organization, help the rebels sneak in? Like sure, Dan's done some nice things for. But aiding what is quite literally a terrorist attack because a friend asks you to? She treats it like it's no big deal.
</spoiler>