Dylan's biographical movie 'I'm not there' is a chameleon just as Dylan is. Director Todd Haynes chose a very unique angle to present the different stages in Dylan's life.
Lets start with the fact that Dylan isn't even playing in the movie, instead there are six other (some more famous than others) actors. Among which are Christian Bale, Richard Gere, and Cate Blanchett. Some more resemble Dylan then others, some are just really far off (Marcus Carl Franklin as a black boy playing Dylan). But Haynes never intended for them to look like him, they are all playing other characters in various situations that just happen to bring the life of Dylan.
One thing is for sure, the soundtrack is great!