OMG.
First of all, the book by John Boyne was one of the best pieces of literature I have ever read in my life. It was written so simply, so we get to see the Holocaust through the innocent eyes of a young German boy, but at the same time we know the horrible context that surrounds it, while little Bruno slowly discovers it. That is one of the things that makes the book all the more powerful. The other most powerful element in the book was the ending, which, if you haven't read it, is so shocking that it will drive some of you to tears. Yet Boyne never forces any emotion on the reader--he merely tells the story from the naive point of view of young Bruno and the emotion just ends up coming along with it.
Watching the story play out in film format was even more powerful than reading the book, because we actually get to see the tragedy play out. The film puts a bit more emphasis on Bruno's parent's POV than the book does, but this works very well cinematicallly and makes the ending even more emotional. And, in terms of the ending, although I had read the book before seeing the film and already knew what happened, the phenomenal blend of excellent cinematography, acting, directing, and musical score left me just as shocked (if not more so) as I had first been when I had originally read the end of the book. So shocked that I couldn't even bring myself to tears. But it was incredibly moving...in a terribly bittersweet way.
Personally, I think it was the best film of 2008. Definitely worth seeing, and the book is definitely worth reading. Incredibly sad, yes, but the story has such a huge impact that it will leave you stunned for days.