The problem with this in the Hobbit is that it's just kind of...thrown at the viewer. There's no sense of unfolding grandiosity, which I always liked about the story. It starts off small, and is constantly implied to be larger, and eventually Bilbo learns just how large it is. Instead of this gradual process, we're given the entire Dwarven back story right off the bat, and the movie is never allowed to have any mystery. Thorin's passionate attitude towards Orcs is answered immediately. The nature of the simmering conflict between dwarves and elves is answered before it's even a question. Unlike the novel, where Gandalf's departures have a certain mysterious quality to them that contributes to his enigmatic nature, the film just goes ahead and tells the audience what he's doing and what he's after. It kills the suspense. Not all the suspense, maybe, but a great deal of it.
LotR used exposition well, especially in the first film, where it very succinctly says what it has to say and gets on with it. But using the same technique in The Hobbit feels like a betrayal of the story's mood and themes.
