Just watched this through for the second time. One of my all-time favorite shows! Collin Morgan's performance and range of emotion is unparalleled. After rewatching the show, he may have just made my top 10 favorite actors list. The chemistry between Bradley Cooper (Arthur) and Collin Morgan (Merlin) is hilarious and genuine, and the story is nothing short of a (platonic) love story between the two characters. My only critique is Katie McGrath's performance/character. Never been a huge Katie McGrath fan, and though it is a tough character to portray I'm sure with the plot twist season 2-3 ish, her portrayal of Lady Morgana is just too cartoonish for my liking.
Overall though, gotta give this one a 10/10. Great family show too (+13, probably a little scary for the little ones)