I'll skip the bad acting, stereotypical characterizations and sum with this: This is a piece of religious propaganda and an inaccurate portrayal of the Dutch under Nazi control and the Dutch resistance.
This movie could only be viewed in a good light by Christian fundamentalist, that care not so much for truth but rather that they are always cast as both the victim and the hero - a characterization not supported by history, let alone by the Christian church's tolerance, acceptance and sometimes outright promotion of the Nazism.
As a movie it was bad acting, mixed with some good stuff. As a piece of history, it was simply Christian wishful thinking and revisionist history.