By Margeaux Watson
Updated November 25, 2008 at 11:41 PM EST

Last night, I attended a media screening of Cadillac Records in New York while my colleague Carrie Bell was on the scene at the movie’s star-studded L.A. premiere at the Egyptian Theater, followed by an after-party at Les Deux. I had been dying to see the film ever since Beyonce Knowles landed the role of R&B legend and ex-heroin addict Etta James. The movie, which follows Chicago-based Chess Records in the 1950s and ’60s, also stars Adrien Brody as label founder Leonard Chess, Jeffrey Wright as Muddy Waters, and Mos Def as Chuck Berry. Working with those guys clearly inspired B to step up her acting game. She doesn’t appear on screen until the second hour of the movie, but it’s worth the wait, as this is her finest cinematic performance to date. Tortured, tragic, and playfully profane, she inhabits the role with fiery conviction, though it’s certainly the most sanitized depiction of a junkie I’ve ever seen (Trainspotting this is not). The only major drawback to her performance is that she lacks the pained vocal chops to convincingly pull off James’ songs or make them her own like Diana Ross did with Billie Holiday’s standards in 1972’s Lady Sings the Blues. Each time she covers classics like “At Last” and “Trust In Me,” you hear Beyonce, not Etta. Apparently, James agrees. Last night when Carrie asked her how she felt about Beyonce’s portrayal, she replied, “She did her thing. She sings good, but I don’t think she sings as good as me.” True that, diva.