I don't care about 'one shot' or movie mechanics, etc. It was an interesting period piece, the characters were very believable in the roles.
The countryside, the bunkers, and the war scenes were 'mostly' realistic. I'll put a 'mostly' in here, as some of the mangled corpses look more like a horror film, than anything you could see in battle in real life. It was all exceptionally gory, and that I found to not be realistic. The way the men acted, lazy, shell shocked and stressed was realistic. The countryside appeared so perfect for those times. I was really impressed.