Taking some liberties with the source material is hardly a new phenomenon starting with The Hobbit movies - film, after all, is a different medium and what can work effectively in the written word might be lacking in cinematic appeal, so changes are inevitable. Some of the alterations made by Jackson and his co-writers from Tolkien's original book can be viewed as necessary evils to make the film flow more smoothly - others, however, seem rather pointless, and sticking to the source material would've been a far better option. We've already discussed the shoehorning of The Lord of the Rings references, but other deviations which the film suffers from include everything from the appearance of some of the characters (Bilbo and Thorin have both been given a Hollywood-style face lift) to omitting key scenes, for instance when Bilbo tries to escape from his home to avoid going on the adventure (an aspect which would no doubt have livened up that lengthy sequence). Jackson creates out of place tension where Tolkien had none, and sometimes adds unnecessary characters in order to achieve this. Perhaps the most glaring example is the introduction of Azog the Defiler as the central villain - a more one-dimensional, bland antagonist you'd be hard pushed to find.
