I was particularly charmed by the fact that the BBC have managed to include black characters. The setting is vaguely Medievaloid and it would make more sense if it were were clearly post-Roman Dark Ages as Guinevere's father or grandfather might then have come to Britain with one of the legions, but hey! Who cares? Nothing else makes all that much sense, so just sit back, put your critical faculties to one side and enjoy. :)
A quick Google shows that the show is getting crap reviews, but I rather like it. Just don't expect it to follow any previous version of the Arthur myth, that's all! It's as though they've put all the different characters and plot elements onto small cards, dropped them into a hat, given it a good shake and pulled stuff out at random, but as a non-challenging fun drama, I think it's fine. So much better than the interminable serial killers with increasingly weird and horrible methods of killing their victims (usually female) that seems to be the current adult TV fare.