And it almost succeeded in getting them to kill each other. I thought this episode worked well. There was no threat except whatever they imagined. It gave some back-story on Shepard. There was continuity with McKay still winging about the arrow in his butt. No explanation on why Teyla was not affected though.
Enjoyed this episode, even though it did little to advance the story arc. It did give more back story to Sheppard, which didn't necessarily affect his character as it stands.
It was obvious that McKay was being affected by the machine when it started to go wrong. He kept leaving the hub of it, thus leaving himself open to the psychic attack.
I think that Teyla was not affected because of her unique part-Wraith physiology, possibly making her less susceptable to their psychic invasions. That and the fact that she's already gone probing the hive mind so would have built up any defences she had.
It was a pretty good episode but there was just too much going on. Ronon and McKay's "visions" were virtually abandoned and only thrown back in as a plot device.
I liked the way that McKay bullet wound miraculously moved from the left hand side of his chest, just after Sheppard shot him, to the left hand side of his abdomen as Beckett was bandaging him up!
It seems to me that TPTB are purposely ignoring Ronon and Teyla for some reason. They refer to Teyla's Wraith DNA occasionally but they never do anything with it except have it as a plot device.