The most difficult part about the movie, is actually the name - for this first installment of the Hobbit movie franchise, covers far more than the story of the Hobbit, and also delves into other stories from Tolkien's Middle Earth.
But it all works. It is a composed story that flows, and makes sense. After the movie, M, commented that she didn't remember The Hobbit being so epic. And that is why this movie works; it is not only about the adventure - it is about a wider story arc with a rich back story that has been interwoven in the tale. I saw it in the 48 frame project (only in Sandton and Gateway apparently); and the cinematography is just amazing. I am not a fan of 3D movies; but this is one where it works.
If we treat this to be a part of a wider series of movies based on Middle Earth, then the movie works well. Given the success of "Game of Thrones", perhaps this could have worked equally as a set of mini-series; but it wouldn't have looked as majestic and epic. Ultimately, that is what movies are for.