Ok, except for lack of color
This movie was actually an ok viewing, save the stupid choise of making it almost black and white. Especially the bunker scenes are lacking all color.
And this is a poor creative decision, as production value was quite good, as they clearly spent the money to make the gore physical effects rather than cgi, but all the viscera and blood is yellow, a trend that several movies in this genre have been a victim of, one of the saw movies comes to mind where the blood was purple. I HATE THIS STUPID TREND. If you make horror, have the decency and balls to show the gore in correct color, we who watch this are not babies that need pampering or protection from gore effects, we actually watch these flicks BECAUSE it contains blood and guts, and we enjoy watching proper made gore effects.
I suspect the lack of color might be due to political correctness and the nazi theme, complete with armbands and uniforms, so not showing the red colors tone down the nazi theme,and also makes blood yellow. Again if this is the case, you should stop making movies you cannot support fully.