I want to say the acting is bad, but I think it was the directing that made it so. I never thought much of Highlander (same director) but that one could be blamed on the 80s.
This one however, has no excuses. People get shot while exiting trenches with a man in front of him!? Those kind of mistakes, along with an unclear time line, weird battle tactics, sub-par cutting and poor visual effects, makes this one a sub-par film over all.
Then like so many other have commented, all this American bullshit. The German general being practically scared of his captured American private. Be prepared to swallow a lot of it, although in small doses.
To sum it up, a not horrible but still definitely sub-par war movie in all aspects.