It's proper gory and very violent, and it has an air of darkness and brutality about it that really sets a grim tone. Stick some bearded guys throwing spells about in there and you've got a Dragon Warriors movie.
It's very wrong about the seige of Rochester and, if done properly, a movie about that important moment in English history would be all kinds of dramatic. But, in true boy's adventure fashion, the film makers decided to drop all that and go for 'this is what a greatsword can do!' and 'double-headed greataxes are awesome!!!' instead. It's got some great performances and it's worth watching for an amazing speech by King John (played to the hilt by Paul Giamatti). This is a great film and pleases me on so many levels.
Currently, as far as TV shows and movies to inspire a Dragon Warriors game goes, I'm listing the following in order of suitability:
1 - Robin of Sherwood
2 - Ironclad
3 - Black Death
4 - Cadfael
5 - The Name Of The Rose
6 - Arn: The Knight Templar
I'll add to the list as time goes on.