Yes the background can be annoying - I have to point that out. Although I think I am pointing out the obvious. Something everyone can see - no pun intended. But something that hopefully won't bug you too much. Not sure if there was another (cheaper solution) to this, but the movie does concentrate on the ... story and the characters it has. Which is a good thing and should be the thing you should look forward to the most.
That said, the actors really deliver here. Even someone like Matthias Schweighöfer or anyone else who has a small (insignificant or not) role or a bigger one. This is a murder mystery ... one where our hero seems to have something hidden himself. Or something that haunts him from the past ... and not just the fact that he was in a war. The ghosts that haunt him from that are big too of course.
There is enough to sink your teeth in and relish in where the story takes us. You can't be squeamish though, because there are some scenes that can be called borderline and quite violent. But it is the nature of the movie and our main bad guy ... tough case to crack. A Sherlock Holmes would be a nice thing to have - but maybe the former police man is able to find the culprit too ... you have to watch to see! And also if his journey is ... well let's call it complete.