Dreamgirls is largely based on the story of The Supremes, the ground-breaking Motown group. However, the movie does them no justice. All the music in the movie was written especially for the movie. So you don't have any recognisable 60s songs. Plus, the songs are quite dull and don't really capture the sound of the 60s or of Motown.
Throw in a rather linear script and unimaginative direction and the movie is nothing special. Plus, in a movie filled with musical performances, the director has random music-instead-of-acting scenes, like in a musical. It just seemed like overkill and totally unnecessary.
Decent performances though. Eddie Murphy got a Best Supporting Actor Oscar nomination and Jennifer Hudson won an Oscar for Best Supporting Actress. Not sure she deserved it though - she was good, but not THAT good. Then again, there wasn't much competition in that category in 2007.
Favorite Scene: Hudson singing and I'm teling you.