Brad Wilber is probably a very nice guy but he's in a bit of a rut. This is his sixth NYT puzzle and every single one is a Saturday. That's just showing off. By which of course I mean congratulations!
This one (answers) is a bit of a curate's egg meaning it's good and it's bad. Actually it's pretty good, I just wanted to use that phrase in a sentence. The derivation is something about not criticizing the fried egg on your plate because, really, parts of it are just fine.
This puzzle was a blast from the past for me. First, the greatest Brünnhilde of all time is Birgit NILSSON right there at 47 Across. Nice to see that name being clued without a reference to Me and My Arrow or something similar. When you watch Elmer Fudd sing "Kill the Wabbit" or hear helicopters racing across the screen in Apocalypse Now, that's Ms. Nilsson's theme song. She was also the quintessential Turandot and owned the role of Isolde for years. When asked for the secret to her success as Isolde she replied, "sensible shoes." More past blasting came from ALARUM, a word I learned from an O. Henry story, complete with PLOT TWISTS. Then there was I'M CALM which is Hysterium's big song in Sondheim's A Funny Thing Happened on the Way to the Forum. All is all, a puzzle designed just for me. Thanks, Mr. Wilber.