Unlike the last two screen examples of Arthuriana, I've seen, King Arthur and The Last Legion, there is no attempt here to do a 'historical Arthur'. Instead, it's all set in a timeless quasi-mediaeval fantasy world (seemingly using leftover sets and costumes from Robin Hood). In general, I approve. When Geoffrey of Monmouth and Chretien de Troyes wrote down these stories, the main fonts from which all subsequent versions come, they set them in a timeless mediaeval fantasy world. Doing a historical Arthur strikes me as slightly missing the point.
Gwen from Torchwood! Actually showing more acting skills than she's ever displayed in that role.
Richard Wilson's frightwig is rather unsettling.
The music, overly dependent on Howard Shore, and over-emphasizing the emotional content of each scene, which seems to be the fashion these days.
And there's not much of a sense of otherness about Camelot. Everyone talks, behaves, even to a degree dresses as if this is 2008 London. Roll that up with a bunch of cliches (the bullying prince, the servant who saves everyone but can't tell), and, though this is not bad, it doesn't climb much above most other semi-competent Arthur versions.