4. The Dwarves
Given that there are thirteen dwarves in The Hobbit, finding an economic way to introduce them to us is paramount, yet despite his 169-minute runtime, Jackson apparently can't figure out a way to do it. When we first meet them at Bilbo's home, we spend a while with them yet we're not really allowed to distinguish between them or get to know their personalities, apart from the leader, Thorin, whose back-story is shown in a flashback. In fact, given that we know what happens to Bilbo, Gandalf and Gollum post-Hobbit, they're really the only characters whose fates we can actually get concerned about - at least for those of us who haven't read the book - yet when we can't even remember their names or know much about them, it doesn't promote that sort of investment. The similar look of many of the dwarves also doesn't help all that much, and that, combined with the lack of character development really makes it hard to tell the difference between them. But then if they were developed, the film would probably be five hours long.