The music is great. Jamie Foxx's performance is great, and he deserved the Oscar he got for it (and I thought his acceptance speech was one of the best I've ever heard). And Curtis Armstrong vanishes into the role of Ahmet Ertegun—I didn't recognize him at all.
But the script is beyond hackneyed. If they want to establish (for example) that Ray Charles' foray into country music was a surprising critical and popular success, they'll have a character say "Well, Ray, your foray into country music was a surprising critical and popular success." Bleah.
Much of the movie turns on some facile psychologizing and showbiz cliché. Gee, drug abuse, womanizing, dumping inconvenient personal relationships when they stand in the way of success? Who knew that sort of thing went on in the world of professional music? Anyone who's seen more than three movies in this genre, is who.