Don't disregard this review because of my age but just think about what I'm saying....
This book is amazing and if, like me, you were left with a huge hole in your heart from the first book (The Forest Of Hands & Teeth) then you must read the second book. Carrie Ryan is an amazing author who manages to keep this series reasonably light-spirited while bringing in dark scary aspects. The book will leave you paranoid and wary but it is most definitely worth it! If you don't mind being scared a bit then this book is fine. The love aspect is ok for anyone to read I think. There are more explicit things being done in the street (kissing etc.) than what is described in this book.
You need to remember that the character Gabry is in a very extreme situation which makes it almost ok for her to commit the crimes she did. But she is not a good role model for anyone to look up to.
The violence in this book is probably the worst thing, with beheadings and other body mutilations described rather graphically. It is not so much the gruesomeness of the words that is so disturbing but the ideas behind it and the feelings; or lack of. But if you think about it, kids these days are seeing and getting accustomed to this extreme violence and torture through video games like COD etc.
Overall this is a great book and if you've read the first then nothing should keep you from reading this or the third book.