The boy in the striped pajamas: book review

I finally had the opportunity to read this highly recommended book (which is also a movie) and I have no words to describe how much it moved me. As a matter of fact, I saw the movie when I was at the beginning of the book (I´d rather do this so I don´t get too disappointed in the movie, cause books are always much better and richer in general) and even though I was prepared for a very sad ending, I couldn´t help crying. 
I had already read books about the Holocaust (The Book Thief and The Diary of Annie Frank) and I´ve pretty much enjoyed them, is spite of their inevitable sad endings. This book is about a very naive nine-year-old boy (Bruno) who has to leave his hometown (Berlin) behind to move to another part of the country (Auchwitz, which Bruno gracefully mispronounces as "Out-With", a very clever pun. The name of the city is never mentioned, though), where his father (who has a high rank  military job) was sent to by "The Fury" (another mispronounced word by the boy) to work in the concentration camp there. He feels terrible about leaving the comfort of his great home and his "three best friends for life" behind to live in a far-away place with no one to play with, not even his sister, Gretel, who is 12 and considered a "hopeless case" by her brother. From his bedroom window, he can see a fence and lots of people (men and boys, but no women) wearing "striped pajamas", but he doesn´t have a clue who those people are and what they´re doing there. His mother isn´t thrilled about the place either and his father is too busy to talk to him. One day, feeling too lonely, Bruno decides to explore the place and, by the time he gets to the fence, he sees a little boy sitting on the other side and they start a friendship when Bruno repeatedly go back to the fence, although he never says a word about this to his parents, afraid of being punished (his sister and his tutor tell him how bad the Jews were). On one side there´s Bruno, a kind-hearted, well-nurtured and naive boy who´s never suffered any hardships in life and on the other, Schmuel, another nine-year old (they share the same bithday date) but much skinnier, paler and sadder than his pal. Schmuel tells a little about the "other side of the fence", but Bruno can´t really picture the kind of life they lead there: the cruelty caused by his own father and his soldiers and the idea of a concentration camp.
One can´t help falling in love with this story and its characters: so much love and kindness between two completely different boys compared to the coldness and the horrors of this dark period in the World History.