Amy Tintera also wrote Reboot, which I didn't realize until I was partway through Ruined. They are very different books. Reboot is scifi/dystopian and Ruined is fantasy. Still, though, I could definitely tell they were written by the same author. I found them to be the same sort of readable.
Ruined is the story of Emelina and Casimir. I just realized that although we know Emelina's last name, I don't remember ever learning Casimir's, which is a little odd. Em is the oldest daughter of the queen of the Ruined, but is not in the line of succession due to not having inherited any Ruined powers. Her parents have been killed and her sister Olivia, who is now queen, was kidnapped. Em hatches a plan to save her, which involves impersonating the princess of another kingdom who is due to wed Casimir, the prince of Lera, the kingdom that took Olivia. As one would expect with this set up, romance blooms between Em and Casimir despite the (epic) differences of their kingdoms.
I liked this book. I enjoyed reading it. I wouldn't say it's the best ever. One reason would be that it was a bit predicable...but that doesn't always turn me off, so that's not all. I also don't love when books end without really ending. This is clearly book one of a series and the ending reflects that. What I do like, though, is strong and independent Em, Em's friendship with Aren, the wit and humor that comes through in a fair amount of the dialogue and the growth of the characters (this last is also a down, as it's fairly predicable). When I talk about the lacks of the book, it's not anything major. I did like the book.
I'll be passing Ruined onto Davan. Also, reading it made me realize that I don't think I ever read Rebel, the sequel to Reboot. I'll be checking it out, as well.