Dreams with Sharp Teeth has interviews with people who knew Ellison, but it's mostly Ellison himself, telling tales, reading from his stories, being himself. I found it irresistible, though as Ellison says, he's great dinner company, but you probably wouldn't want to live with him. He doesn't hold anything back, ever. For him, there are no battles not worth fighting. He's a fascinating guy, a fine oral storyteller, and a superb interpreter of his own writing.
My only complaint is that Ellison didn't tell anything about breaking into the SF field, about living and writing in New York, his association with Regency Books, and so on. I wish he'd write about those early days. It would be fascinating reading. The fact that those things are glossed over in the film, however, shouldn't stop you from seeing it. If you've enjoyed Ellison's work, you owe it to yourself to take a look.
Update: I've been informed that this is now available on iTunes. Check it out.