so I finally saw this last night. It was ok. Average I guess. Not very Arthurian in any way, taking a lot of liberties even with some less well regarded theories of origin, and nearly offensively trying to justify itself with 'historians agree' (no, not many of them anyway).
What really took me out of it, though (since I went in not expecting it to be faithful) was the sometimes completely incomprehensibly chosen shots. the direction was pretty poor. shots that had nothing to do with anything. it seemed the main reason many shots were included was not that they contributed, but that they "looked pretty."
the little speaches were a bit annoying too. I would have felt it much more inspiring if Arthur had shut his yap before the last battle. And there was almost no voiceover worth including though they did anyway. the cut 30 seconds where Merlin says 'No fate is shared' was pretty cool. I'd have left that in.
finally, what was up with cerdic. He had neither a commanding voice or an intimidating presence. He was always looking at the ground, and he never spoke in anything above a whisper. Ugh.