Seriously, I cannot say enough good things about this series!! 
 I will say that while the ending is good enough, I kept hoping for a cure, an answer, an end to the suffering. And at the same time, I kept expecting them all to die. To just say that they give up and jump. 
 The book kept me guessing as to what the ending actually would be until the end. Not an 'edge of your seat, can't stand the suspense' kind of way, but fantastic nonetheless. 
 It's obvious that the book is open ended, leaving way for a new generation's story to be told, but could just as easily be an ending. 
 If I had my way we would get two more books: a prequel to learn how it all started and an ending book to either end the zombies or end the humans. But who am I to say, I like a solid ending.