I saw in the theater over summer, very good film... I enjoyed the interesting way in which the film took some of the convention of the film noir and turned them upside down... enjoyable to say the least, not perfect, but good.
Film noir is was a term French film critics gave to American movies that were made just after WWII... moody black and white movies that focused on mostly on detective and crime stories... some of the great Film Noirs from the classic period are the Big Sleep, The Postman Always Rings Twice, Out Of the Past, the Maltese Falcon, the Asphalt Jungle, and Murder, My Sweet.
Film Noir has been revisited again and again by directors since the late 40's and early 50's... films like Chinatown, the Long Goodbye, L.A Confidential, Resevoir Dogs, Blood Simple, Fargo, the Usual Suspects are modern noirs or draw inspiration from classic noirs.