The story is captivating and compelling, while some of the twists may be a little off-putting. The plot, in short, pits the king of Camelot against all forms of sorcery. This is troublesome because Merlin, the greatest sorcerer in history, is the once and future king Arthur's personal servant. The tension between Merlin's desire to help Arthur and the fact that the practice of magic is illegal fuel the entire story.
The first season is light and fun to watch. Clearly, the special effects budget increased as the show continued. After a couple seasons, random episodes take on a dark nature until it climaxes with war for the future of Camelot.
A lot of the legend of King Arthur is presented here, though clearly the creators take liberties to tell their own story. If anyone finds that offensive, I suggest you look elsewhere. The myth weavesd here is excellent and entertaining.
Overall, I give this TV Show aired on BBC five stars and a hearty recommendation. Now I need to find something else to watch on Netflix!