Couple of notes: 
 This one flowed really well. YA sci fi with some romance, but not a whole lot. 
 Following two characters who alternate chapters. 
 Amy is frozen and put on the Godspeed with her parents and other colonists for the long 300 year journey to another planet. There is also a crew that keeps the ship going, families who live their entire lives on the ship and their kids take over the next generation of ship's crew. Then she gets woken up 50 years early. 
 Elder is the future leader of the Godspeed, living in a highly regimented society founded after the Plague decimated most of the ship's crew. He is set to take over from Eldest soon, but although he has always respected him as a leader, Elder is having doubts about what he's been told. 
 Amy is thrust into a society so bizarre, she can't believe everyone is human, and although she wants her parents with her, she is also scared because someone keeps unfreezing people, and people are dying. 
 Lots of questions on what it is to be human; is it better to have total peace or individual truth, how much do we need lies in order to live. 
 Can't say that any of the themes were new for me - have read them before, but I do think that this book is a good way to get new, younger readers into sci fi. 
 Some violence, sex, and an attempted rape make it a bit more adult than other YA.