When this episode started, I didn't have very high hopes for it. The whole casino incident seemed kinda dodgy and unfunny, and was, in my opinion, a poor way to get Martin out of of there (though Homer's PlayStation One line was mildly amusing to this gamer). After that, though, things really picked up. For once, there were jokes that not only made me snicker but also made me laugh loudly! Lisa's indifference to gym, some of the antics of Milhouse and Willy, Marge believing herself to be in trouble after saying "fudgerucker" (or something like that), Chalmers's treatment of Willy (including his "taking advise from the janitor" line)...these sorts of excellent jokes have been sorely missing from the more recent seasons, and I probably haven't enjoyed myself with an episode this much since I don't know when.
Of course, I know come to the singing portions of this episode. To be honest, they weren't too bad. They didn't annoy me or fill themselves with too many unrealistic elements (the Evita inspiration being acceptable here), and it was nice to have some songs in the show again. The plot itself wasn't too disjointed or went too fast, so I could absorb the jokes and such a bit better.
So, besides part of the opening and a few odd things here or there (As somewhat amusing as Homer prancing about in a tutu is, it was just very strange), I really genuinely enjoyed this episode. 4/5, best episode so far this season.