This is certainly a white washed version of what the English suffered during the first years of the war. It was made as a propaganda film that was meant to inspire American support and end the isolationist policy and feeling that had been prevalent since the end of World War 1.
"The film won six Academy Awards, including Best Picture, Best Actress, and Best Director."
It's a bit fluffy and melodramatic, but a fascinating to observe piece of pop culture and a must see for that reason alone.
Get some pop corn though. It's so long you could starve by the end.