The reasons that The Devil Wears Prada is awesome are many: Anne Hathaway is good for looking at, and both leads are great actors, and the "cerulean blue" speech is the most concise explanation of the connection between commerce and art I've ever heard. But the reason, I think, that it will live forever is that it tells a very awesome, very old and necessary story, and it does it very well. Psyche falls in love with Eros in a classic Beauty & The Beast story where she can't look at his face because he's a God and that's way heavy. Aphrodite steps in to say that she can't be with him until she does these tasks, and each of these tasks -- although very feminine in connotation -- forces Psyche across the line from emotion to logic: separating seeds, cleaning up messes, stealing golden wool, going to the underworld for Persephone's cold cream, etc. The story's undervalued because women's experience is undervalued, and you need look no further than this show's success -- which will always be partial at best precisely because of the high feminine/gay/fashion/camp/soap element present -- to know that this is still an issue.
But the story itself is essential, and informs a lot of later fairytales (particularly Andersen, who really just wrote a billion riffs on this story and created the best fairytales ever as a result). Really what it's about is the duty of young women to make contact with their internal masculine pieces, so that they can look at their beloved head-on, and see him as another person instead of a projection of her own stuff. Men are just people, not misplaced pieces of ourselves, because we don't misplace pieces of ourselves anywhere further than our own backyard. Miranda teaches Andy to be hard, logical and smart, which is to say she gives her options: go back to the creative writer you were meant to be, or take Miranda's path. And that's present here, at least in gesture, but only if you look at Betty and Daniel as two halves of the same person: she teaches him to see his own masculine face in the mirror of Mode, and accept that for good or ill he's good at editing women's fashion. But she couldn't accomplish any of this without the help of Mark's usual secret and undervalued wizardry, and Wilhelmina's Aphrodite machinations, which is how all myths and fairytales work: not the tools you already know you have, but the adverse circumstances and surprise potentials all around and within you. So there's that.
Anyway, it's a weecap. The party is, of course, so totally scary. You've got ice sculptures of people, and models dressed as angels, and the music is quietly going "uh!" in the background like a porno on a loop or a video of an old lady falling down. Betty notes that Wili isn't wearing Tiara the Great, and Wili's like, "I'm EIC of a fashion magazine?" Betty is unsurprised and hands over her two week's notice, because she apparently needed a whole episode to notice that Wilhelmina Slater is a bitch. Wili mourns the loss of what would never have actually been, complaining that "under those gaping pores and caveman eyebrows," she thought she detected an intelligence in Betty. Like that genius idea to sell products in the pages of a magazine? That was fucking amazing.