I didn't mind the ending to The Devil Wears Prada (the following two paragraph contain SPOILERS for The Devil Wears Prada, and is a bit rant-y, I suppose). I didn't find her friends that irritating (certainly, I didn't care about any of them, but still - they didn't take away from my enjoyment of the film either). Sure, her female friend got a little bit irritated in the gallery but it was perfectly justifiable (she is also friends with Andie's boyfriend, and thought she saw her cheating).
A lot of these type of films end with the lead character completely changed by the end of the film, for a stupid reason (comprimising a bit of herself for the love of a man because a wedding is everything in romcom land), but it wasn't the case in this film. The job changed Andie (obviously she didn't become a full-blown psychopath or anything, but going to Paris, etc. didn't seem like things she would have done before Runway). The talk with Miranda in the limo helped her realise this (great scene, I bet this is why Streep got the Oscar nomination), she quit, and ended the film in a better place because of it.
Hathaway, Blunt, and Streep rocked the movie.