Although it is happening with less frequency, it is still getting a bit old seeing Anne Hathaway transform from nerd/frump to Princess/Princess/fashionista. Hathaway (Brokeback Mountain, Hoodwinked) has been getting a bit more adventurous in her roles, and Andy Sachs feels a bit like a transitional one. It straddles the more teen/kid oriented roles and adult ones, which is where she is in her career. This is primarily because The Devil Wears Prada is based on the novel by Lauren Weisberger. The novel falls into the category of "chick lit," which is typically geared towards women in their young twenties. This is right where the Sachs character is, and right where Hathaway is.
It also helps that the story is funny in a way that anybody, not just young women can understand. Sachs is a college graduate looking to begin a career in serious journalism. Instead, she lands a job as an assistant at Runway magazine, a high fashion magazine edited by the domineering Miranda Priestly (Meryl Streep, A Prairie Home Companion, Prime). Priestly is domineering, demanding, dismissive, and altogether a real nightmare to work for. She hires Sachs because Sachs does not know of Priestly's monstrous reputation, and because Sachs is so different from everybody else in the industry.
The Devil Wears Prada begins with Priestly's other assistant, Emily (Emily Blunt, My Summer of Love, Boudica) and co-worker Nigel (Stanley Tucci, Lucky Number Slevin, Robots) staring down at her through insulting eyes. They look down on the fact that she does not dress "fashionably," and is a not rail thin (although looking at Hathaway, this is hard to believe). Sachs quickly finds herself in over her head with Priestly's bizarre demands and rigorous structure. Still, she's smart, and eventually figures out how to please her insane boss. The catch, is that this comes at the cost of her social life. At the beginning of her job, she mocked her coworkers. Slowly over time, she became one of them.
Thus, director David Frankel (Miami Rhapsody) and adapter Aline Brosh McKenna (Laws of Attraction, Three to Tango) turn The Devil Wears Prada into the prototypical coming-of-age movie, albeit with much more expensive clothes. Sachs needs to figure out what she wants in life, and this is hard because she doesn't know who she is. Life at Runaway is eye opening, because she realizes that this world she dismissed is not as superficial as she thought. The role is a good fit for Hathaway, because she has an innocent likeability about her. It's easy to empathize with her big eyes and squeaky voice.
Streep is even better. Her Priestly is hilarious. People bow to her every whim, and she has the power to end things with a simple "that's all." In her character are glimpses of everybody's worst boss, and Streep conveys everything with a minimum of emotion. As funny and evil as she is, Streep and Frankel do not turn her, Emily, or the others into caricatures. This is what makes The Devil Wears Prada work. Priestly is horrible, but she is smart, and she is driven. She is the way she is because she's good at what she does, and she's erecting an emotional barrier around herself. There is enough substance with the characters to give them film more than just a comedic effect on the audience.