Now that Jennifer Hudson safely got the Oscar and had her day, I can finally voice my reservations about Dreamgirls and that song.
Firstly, as Jennifer Holliday explains in a recent interview, that song basically ruined her career. She was more or less Effie herself when was cast in the role, which she played a significant part in expanding into both acts of the musical (originally, that song was meant to be her swan song). Just a teenager, whose talent and ambition got her basically used and dumped by show business. It was pretty desperate and ungracious to sing it Oscar night from a neighboring roof-top, but basically, whose to tell her she hasn't the right? The song both made and ruined her career.