I agree it was good having the bad guy as some mid level politico dropping hints to people how to wage the war "better". My real complain was once that facade was gone, he really did not look all that impressive in the armor, it was pretty cheesy along with the slow motion stuff. Not a huge deal, but I guess I expected something more from god versus god fight.
The Ludendorff stuff probably did not matter to the VAST majority of people seeing the movie, I just thought he was portrayed so badly and him dying when he played at least a moderate roll in 1920s German politics ... it just took me out of the movie. For me, it would have been better just making up some German sounding name instead of using that one. Again, I doubt many noticed this at all .. but it bugged me. Obviously these are not history movies, but if they are using historical characters, I would think they would have made more of an effort .. or maybe they did and realized they picked the wrong guy .. and just went with it anyway.
I am not a big fan of the super hero movies in general, most do nothing for me and see very much the same as all of them, I think this one was better than most and I enjoyed it.