What a good episode! Great characters, great performance. That's what a good Merlin episode should be.
What I like most:
1. Arthur's reluctance to fight his father (Good job, Bradley, esp. during the fight)
2. Merlin's conversation with Gilli (Great perfromance from both actors; some questions are asked, but I don't think we get a good answer. I think Gilli might be one of the best guest stars we have in S3. In my opinion, Gilli is a better written character than Merlin's other friends, Lancelot, Will, and Gwaine)
3. The last scene between Uther and Arthur (I love how Uther knows his son, yeah! And I like that in this episode Arthur made decisions on his own, without Merlin helping him secretly, or Gwen preaching him. In 3x10, he was totally OOC, but in this episode, you feel the boy grows up overnight.)
Other things I like
Arthur isn't mean to Merlin (now I believe what Bradley said in 3x01 commentary, in the last three episodes, I think Arthur will be less prattish.)
Gwen-free episode