Although this is classed as a Sci-Fi novel I would recommend it lovers of Fantasy/Adventure/Dystopian due to there being more Fantasy elements in the story than Sci-Fi. There is futuristic elements but nothing particularly heavy - unless a futuristic coffee machine is too much for you. It also reads like a fantasy novel. 
 Kelsa and Raven fight like an old married couple which is quite hilarious. There's plenty of sarcastic comments in here! I really enjoyed this story, especially the suspenseful moments but... I was disappointed with the ending. I felt it was rather rushed and not the ending I was hoping for. For instance, as you'd expect, Kelsa and Raven were flirting with each other all the way through and I was waiting for them to get their act together and at least kiss. There was barely a cuddle! That was very disappointing, especially as that's what you'd expect from a YA novel.