I loved this one! A lot of things that I loved, people have already mentioned:
-The tension between McKay and Cadman was great. I love that McKay is still weirded ut by the events of Duet.
-Loved the 101 Dalmations (I'm a Disney freak!) and LOTR mentions. I thought it was hilarious how he mentioned LOTR, and suddenly the scientists got the idea.
-Kavanagh - the man I love to hate. He got some great scenes in this one. Being verbally shot down by an Asgard - how embarrassing! I also love how he fainted, that was priceless. I thought it was great to see him get some real character opportunities in this one, to be put in the position where his past actions made him look like the bad guy when he really wasn't.
-Zelenka with the kids... I would so love to hear the story on that one!
-I thought the song was very pretty. Felt a bit out of place, maybe, but I did like how they used it as the background to the montage. Rachel has a gorgeous voice! The dub on it was pretty shoddy, though.
On a different note, though, I felt like this episode was another big step for Weir. We're really clearly seeing the changes she's starting to go through. I can't imagine her ever authorizing torture like that at the beginning of the series. She would have argued against it vehemently. And I absolutely loved that there was a scene at the end where she did reflect on what she did - it wasn't a "shouldn't have done that, oh well" kind of a deal. She was really genuinely upset about what she did. Loved that scene! And I also loved her little sparring matches with Kavanagh - he really fired some zingers at her! It seemed to me like those insults were really stinging her. She pulled back a bit when he said that, almost looking like she was hurt and trying to hide it. Despite the fact that those insults came from Kavanagh, that's still gotta hurt.