I saw it a few days ago. I'd give the film a C . I felt the weakest aspects were The Richard Gere, Heather Ledger segment's. The child Dylan and Blancett Dylan were the best IMO. Actually I would have liked to have seen a whole biopic with Blancett as Dylan the Protest/Folk singer, Rocker, Country Artist, Domestic parent. She was really the only actor IMO to capture the Legend . Bale was alright , but he didn't get as much time as Ledger.
I could see what they were trying to do with Ledger but it just felt flat to me . Richard Gere's Billy the kid segment was like.... wtf, For me anyway.
The film also lacks much of Dylan's signature tunes such as It Aint Me Babe, Blowing in the Wind, Lay Lady Lay, A Hard Rain's gonna fall , My Back Pages , Don't think Twice it's alright etc. However it does feature All Along the Watchtower, Maggie's Farm, Positively 4th Street, and Like a Rolling Stone in the closing credits . Most of the other ones I didn't recognize . I agree that you've gotta be a die hard Dylan fan to really enjoy it.
Overall I think I would have preferred more of a straight forward biopic with the different aspects of his life rather then using 6 actors with different names. However , the film itself is about the different sides of dylan as opposed to a biopic such as Ray or Walk The Line . I think if the film gets you interested in Dylan , you should watch No Direction Home.