Hm. I think 2x04 is one of the best put together episodes to date. The humor's back on, but better timed than it was in 2x01 or 2x03 (where it sometimes felt off-pace and a bit forced; still funny, but not as naturally integrated.) All the main characters get a moment in the spotlight and most of them get a solid, competent part. (Morgana in particular had been getting a bit ragged about the edges lately; it's nice seeing her back to being strong and competent again.) Progress is made on the love triangle without being overly cloying. And Lancelot is just love. Beautifully implemented as a character (and the actor, num!), managing to balance all the ideals of courtly love but still managing to stay a sympathetic character rather than an overbearing prat. (One prat's enough for the show, thankyouverymuch.) I still very much love their choice of making Guinevere a servant. It throws an interesting kink in the dynamic and ups the tension.
I like the random parallels they manage between first and second season for the episodes. The second episode of each season featured a tournament. I forget what the parallel is for the third -- I'd have to watch 2x03 again. And the forth episode revolves around Arthur risking his life for a servant. I suspect the next pair of episodes will break this -- though I welcome being surprised by it.
No new episode next week, and the one following, I'm told, is a two-parter.