What have you read that is similar to this book? The Experience. It was about time travel, as well.
Consider the main character: what does he or she believe in? He considers Yvaine and Billy, as his family. He does, whatever it takes to keep them safe.
At the end of the book, do you feel hope for the characters? I do have hope. Yvaine is away from her old life. Her and Charlie can start over. Charlie realized how important his mom was to him.
What is stronger in the book: plot or character development? The characters were the strength in this book. The author painted a really good picture to tell his story. He wanted you to really know each character.
Disclosure: I received a review copy of this book from the author.