This is an amazing book which I couldn't put down for a second. I read it after seeing the nice reviews here and I am so glad I did! 
 The plot is interesting, dark, intriguind; the characters very, very complex, in constant development/evolution. She succeeds in creating a suffocating, unfriendly world in which the two (very different) main characters shine; they have to run away, use their abilities and outsmart everyone, while at the same time you can see friendship, trust and something deeper building between them. I'd recommend it to everyone.