The Black Swan, the latest film by Darren Aronofsky. The director, whose previous film The Wrestler was a critical darling and helped relaunch the career of Mickey Rourke (and was one of my favorite films that year), had originally thought of the two films in the same story, but decided to split them into two separate films when there proved to be too much for just one film. So The Wrestler focused on what many consider to be a low-class performance, while Black Swan did the same with what many consider to be a high art form, despite both being physically taxing and exhausting on their respective performers.
#1 film for 2010. But really, are we surprised?