Saw this. Sure the helmets are stupid, and likely done so the actors could show more "emotion" while jousting. Definitely not needed, as the final duel is pretty well done and you didn't need to see anyone's face to feel the action. While it would have been excellent if they just wore accurate great helms, the final duel was still one of the better medieval fight scenes I've ever watched in a movie, and it showcased the brutality of medieval combat pretty well I think. While the previous battle scenes in the movie are standard Hollywood where swords seem to slice through mail like butter, in the final duel armor behaves like it's supposed to. Pretty good overall, and well acted. I give it a B+.
Realize if you see this it is not a war movie. It has some good battle scenes, but it's more a story of a falling out of friendship culminating in a rape told from three perspectives of the principles involved.