OK then, I'm feeling brave. Please don't be mean to me! I accept a lot of people think it's wonderful (indeed, the person who gave it as a present thinks so) and I don't want to upset people.
Yes MamaGlee it's a novel aimed at teenagers. My son is 12 and was given it as a present (Which I was fine about - my argument is not that it is too upsetting - more the reverse).
Spoilers below for anyone who hasn't read it.
My big objection is that all the great writing about the Holocaust (mostly by survivors, although not always) is focused on the people who were the target of the Final Solution, in all its horror. Jews, Romany peoples, homosexuals, we know the dreadful list. That's for a good reason - those are the people who had this done to them. I found it profoundly disturbing that a book which sets out to be horrifying (and/or emotionally moving depending on your point of view) and to show that the Holocaust was horrific almost beyond imagination does so through the means of a flimsy plot device about an uncomprehending Aryan child ending up dead by mistake. At the end, I felt that the reader is encouraged to feel shock and horror and sadness that this one little boy is going to die, not that millions were already, and would continue to be, systematically murdered. Oh, but that's OK, because he feels that the nice little Jewish boy is his best friend.
I'm also no expert but suspect it may be full of historical inaccuracies - all too slick and convenient.
I don't doubt that the author's idea was sound (communicate the story of the Holocaust through a single individual's story) but what a terrible, terrible way to go about it. No amount of homilies in the course of the story about how "we are all the same under the skin" make it OK.
My son, BTW, thought it was very sad, but was a bit underwhelmed after it had been built up so much by the giver. I haven't shared all my thoughts with him, and not sure whether I will do.