I think this is a great show, but many people are finding fault with how events/characters unfold.Be warned:
1.This show does not stick to the traditional Arthurian Legend, like "The Once and Future King" (which i highly recommend reading).
-it brings familiar characters (Merlin, Arthur, Guenevere, Morgana, Uther Pendragon, Lancelot, etc), but because it is a new take, many of these characters may not match up with what you expect
2. there will be inconsistencies with real history- after all, Arthur and Merlin are myth/legend themselves
3. ...there seem to be other complaints about the show...though i guess every show has those who condemn it. if you want more complaints, go to the discussions
If you are looking to be entertained and you like...
1. Fantasy
2. BBC productions
3. an entertaining blend of mystery, action, horror, and romance
3. Colin Morgan, Anthony Head, whoever the hot guy is who plays Arthur, or any of the other actors/actresses
...give the show a chance. Go into it open minded and see where it takes you

This seems like it is really going to be a great tv show, with motion picture qualities.