I was born and lived in Poland until I was 22. Then, in 1989 I left just before the fall of the Berlin wall. This movie presented me with a part of Polish WWII history that was never taught to me by either the socialist state or here in the West, our "allies". This movie makes you think "what if.." and presents a part of history which could be considered by some taboo, something we should not speak of.
The truth is Poland was used as pawn in WWI, promised alliance by the West (twice) and then, abandoned to Soviets when the Polish problem became inconvenient to deal with Stalin. As I said, many "what ifs" were brought by this film in my mind and I would certainly recommend it to anyone who wants to know more beyond the established "history".