First of all, this film is NOT the story of Diana Ross & the Supremes, no one in it sounds like either Ms Ross or the Supremes & there are no obvious Motown sounding songs in the film.
The film's story does take bits of the Supremes & Motown's history & clearly intends viewers to make the connections.
As such, 'Berry Gordy' (Curtis Taylor Jr. in the film, well acted by Jamie Foxx) comes out badly, being depicted as a money chasing white wannabe, dumbing down the `blackness' of his acts in order to sell records to (white) pop music buyers.
What the movie doesn't do is put this in context; making a success as a black person in 1960s America was harder than most modern day viewers could ever imagine. If it meant some compromises along the way in putting black artists on TV & in the charts & out of poverty then surely it was worth it. Today's black stars such as Oprah Whitney & Destiny' Child have testified how they were inspired by Diana Ross etc.
Anyway, back to the film. The acting is uniformly good, Eddie Murphy shows he can really sing, Beyoncé Knowles shows she can act as well as sing & the film is consistently interesting in showing glimces of a long gone time as well as how tough the music business can be.
In truth, if you don't like soul music then you might find the film boring though the amazing vocal performances of Jennifer Hudson should cure you of that pretty quick! (go to the scene where she sings "And I'm Telling You I'm Not Going" & then see if soul music still bores you!!)
Jennifer Hudson is the star of the film & well deserves the Oscar she got for her performance. Her acting is surprising good but her singing - sounding a lot like Aretha Franklin at her best - is simply out standing, & worth the price of the disk 100 times over!
She shows that Simon Cowell may know what music sells but knows nothing about quality & also effortlessly destroys the notion that singers like Duffy, Amy Winehouse & Joss Stone are `soul' singers.
This is a real `feel good' film that thanks to the quality of the singing, can be watched over & over again!