Interesting to see that Mick Kelly was the writer for the episode - I'm not sure about now anymore, but he's been Al Jean's assistant for a number of years. Definitely a really strong first script for the show. This was the best episode of the season so far. It also seems like they're enjoying tinkering with the opening credits, adding little vocal clips to some of the characters, and continually changing Lisa's sax solo.
This episode had a completely focused and coherent storyline (as well as a nice little B story to keep Homer and Marge busy), and had more laughs than any other episode this season. Most of all, there was just about a perfect balance of heartfelt emotion and an intriguing storyline. Granted, I never thought Kirk and Luanne were going to actually die (the story initially struck me as being familiar to an episode of The Critic, but wound up being hush-hush about the whereabouts of the parents until the end of the episode). What was intriguing about the story was actually the idea of Milhouse and Bart's role reversal, which was briefly touched upon in "Milhouse Doesn't Live Here Anymore". However, that time Milhouse's transition to his Cap City persona wasn't fleshed out in any real way, whereas this time it happened in a really organic and believable way.
Some of my favorite gags included the backyard spider explosion and the scene at the airport. Gaylord Q Twinkledink was a great gag character, and Uncle Zach was a nice addition to Milhouse's family too (his family is becoming pretty widespread). The Solvang airline was a solid visual gag too. Homer reading labels and his song were funny moments too.
The only problem that stood out to me at all was the awkward ending to the second act, which could have more to do with me being anal about continuity (Bart entering the front door and appearing through the backyard door, as well as Marge shelving her glasses for this part). But mainly, I'm just not too into out of character behaviour for the sake of a joke, which isn't to say Marge shouldn't dance and TRY to be hip, but rather she shouldn't know how to do it so well (I know, that's the joke - just not always my thing). But I'm being picky. This was a really solid episode - which also added a step of continuity within the show through the official reunion of Kirk and Luanne. I also thought the ending could have used some more breathing room, just to solidify their return home and return to the status quo.
5/5 (or 4.5 if you wanna be truly precise because of my pesky little complaints)