For me, I find book before movie lets my imagination cast the characters and get the whole story. Then, when the movie hits, I can appreciate the casting, and skill it takes to convert into a screen play.
The other way, I have the whole picture with faces, and just enjoy the ride while getting more of the story.
Not sure what I prefer quite yet.
Well you see, none of the characters in the book have names, and in the film, they don't really have... I can't say much else :P
They are both stunning.