I liked the way the book was written moving from one character to another. The Julia/Campbell story was great and it made you want to see what was coming next. Anna did not seem 13 to me at all. I did like having brother Jesse as part of the plot to show the effects the disease had on the whole family.
The storyline was great but I don't want to give too much detail. I really really hated the ending and read the last chapter twice to believe that yes, that is how the book ended.