When I heard that this film consisted of about 1/3 newsreel footage, I was expecting the worst. Stock footage blended with studio footage is something you'd find in an MST3k movie; three people in a car driving quickly away from a giant lizard and then cut to a different film grain shot of an iguana in a lab and then back to the car. Oh no, the Iguana is chasing us.
The effect can be jarring, to say the least.
But Cooper, so far as I have heard, actually wrote the screenplay for Overlord with the stock footage he was going to use already in mind, tailoring his script so that the footage actually made sense. The movie is shot so that the switch from studio to stock lighting and film quality is barely noticeable. I wouldn't go so far as to say it's seamless--it does take a little while to get used to, but after the first fifteen minutes or so you don't even notice it.
And that's a good sign, that you have to "get used to" the picture for a little while before you feel comfortable watching it. That's the sign of originality. This is a brooding and slow-paced war film, but unlike other such films it maintains a certain lightness in spite of its weighty subject and so avoids coming off as ponderous. No viewpoints are shoved in your face. Hard questions are asked, yes, but you're given plenty of time to try and sort them out for yourself.
This is a movie you have to be wide awake while watching--it demands your full attention, and if you're not willing to give that up then you're probably not going to enjoy it. Overlord is most certainly not mindless entertainment. It provokes thought, and if thought makes you uncomfortable it's simply not the movie for you.
