I love music biopics. This one was no exception; therefore, I decided to rate the performances:

The actors who played Muddy Waters, Little Walter, and Howlin' Wolf were excellent!
The movie was not centered around Beyonce...which was great...she played a decent part...the only thing that disturbed me about her performance was that it sounded like Beyonce doin a cover of Etta James. Other than that, it was fantastic. Mos Def provided comic relief as Chuck Berry. Adrien Brody did a fine job portraying Chess. Overall, I would say go and see this movie. I might see it again.