Princess Ida/YMMV

• Crowning Music of Awesome: The second act contains the so-called string of pearls, which are considered some of Sullivan's most beautiful melodies. The quartet The world is but a broken toy has been called Gounod-esque.
• Crowning Moment of Funny:

Hildenbrand (Gama has been spotted on the horizon): Is the princess with him?
Florian: Well, my liege, unless her highness is full six feet high, and wears mustachios too – and smokes cigars – and rides en cavalier in coat of steel – I do not think she is.

• Ear Worm: This being Gilbert and Sullivan, the trops is inevitable. Aside from the opening chorus, the trio I am a maiden, the duet Now wouldn't you like to rule the roost and Psyche's A lady fair count.
• Ending Fatigue: With three acts, Ida is the longest operetta out of the Gilbert and Sullivan repertoire. Paradoxely, the Last-Minute Hookup still feels very rushed. See the next trope for more.
• Fair for Its Day: the apparent anti-feminism in Princess Ida is nothing compared to the genuine Anti-Feminist jokes of its time. The Tennyson poem it's based on is also arguably worse in many respects than Gilbert's parody, since the Framing Story basically claims it's an incompetent attempt by feminists to rewrite history, which ends up showing that a woman's place is with her man. In Gilbert's version, the worst you get is some characters poking fun of women's education -- before they get there, and all of whom think that educated women are fantastic once they meet them, skewering of some of the man-hating aspects of Ida's college, and a scene where book-learning meets reality, and the woman refuses to do surgery which she was taught to do from books alone.
• Strangled by the Red String: Possibly Ida and Hilarion; he claims to love her, but initially mocks the concept of women's education and shows a few signs of having changed his mind at the end. She resents him for lying to her and loudly proclaims she'd rather die than marry him. And then, oh look, her brothers are defeated/we have five minutes before the opera ends, she's in love now!