I've heard nothing but great things about this documentary. I'm definately looking forward to seeing it.
It sounds similar to a documentary that I saw yesterday done by a Soror called "Finally Sayin What I Really Mean", investigating what is "good music", the "neo-soul" classification, conscious poetry, and mainstream rap. Had great footage of Jill Scott, Cody Chestnutt, Anthony David, Chamillionaire, David Banner, Joi, Lalah Hathaway, and many others. I'd recommend that one as well. Here are some links...
4th Annual Film & Discussion Series - Welcomewww.myspace.com/redheaddread (preview is the first video clip)