There are two ways to look at this book: the cynical way and the not so cynical.
First, cynical. You could just say this is a retelling of the Anne Frank story. However, (SPOILER) with two main plot differences: Sara (the Anne character) is hiding alone and not with her family/other families and she survives the ordeal.
Finally, the not so cynical way allows you to see that White Bird by R. J. Palacio was inspired by all the stories of World War II and was heavily influenced by Anne Frank.
The more cynical feelings were accented by the fact that I read the two graphic novels back-to-back. I had to do a quick step-back and start over with White Bird and see it as its own story and see its merits.
And there are many pieces of this book that are amazingly wonderful. While some areas of the story were romantic, it is realistic. It is also poetic and strong story. There is the mature theme of the Holocaust, but ages 10 to adult reader can partake in it. Though a sensitive reader might have issues as there is violence (the death of several characters and one character is badly beaten).
I would not have given Anne Frank the graphic novel to under 12, let alone the diary itself, yet I feel strong readers will have no issue with White Bird. I loved the fact all types of people were seen: the people who helped in little ways, the people who helped in larger ways, the suspicious natures of people, even how one boy (handsome-all-the-girls-crushed-on) would do anything to please his father: a French collaborator of the Nazis. And therefore, the Nazis themselves.
The history of France is also a part of the story and it is a piece of history not always seen. We know there was the French Resistance, but I was not aware that there was an Occupied zone of France and Free zone of France. Which of course, was about as free as the Occupied zone was. There are a few pieces of history that are given changes to fit the story (one character in the book is female but based on a male person).