Andrea has just graduated from college and opens up her day planner to realize she has an appointment for an interview with Runway Magazine. She somehow gets hired despite being totally inappropriate for the job of Editor-in-Chief Miranda's Priestly's second assistant. She's required to get coffee, hang up Miranda's coat, and many other personal details which have nothing to do with the magazine, but make Miranda's personal life easier.
Although based on the book, the film tries to show Miranda being vulnerable and not a complete bitch every second of the day as in the book, she was. A few things have been changed or added: Andie now lives with her boyfriend, who's a chef instead of a schoolteacher of nine-year old first graders (check with the author of the book on that one), and her best friend is an artist instead of a drunken loser. There's also a male character (Stanley Tucci) who's been working under Miranda for 18 years who tries to buck Andie up when she whines at how Miranda never appreciates her.
Other things stick: Andie thinks that after one year as Miranda's assistant (and so she is told in the book) that she automatically becomes a writer for any magazine she chooses (and if she can't write for a magazine, it doesn't matter because she'll write a tell-all badly written, boring book).
This film is shallow, depressing, and goes nowhere - just like the book. The ending is changed to try to give the story some redeeming value, but it fails.
The acting isn't bad (even Gisele Bundchen is credible in a small part), but with the lame story the actors had to work with, it's a waste of Meryl Streep. And she's the only reason anyone would see this superficial movie.