I've now read chapters 2 and 3 of Tolkien's The Hobbit. Here are some more departures that Peter Jackson takes in his movie, from the book.
Thorin and the elves: There's no evidence in the book that Thorin hates or distrusts the elves, any more than other dwarves do. There's no baggage or history here of resentment and distrust. There's not fussing between Thorin and Gandalf about such things. When Gandalf tells the dwarves that they're going to Rivendell to rest, they're fine with that. All that conflict in Rivendell when the dwarves arrive? Not in the book at all. Rivendell is a valley with a house -- the last homely house. It's not an elegant city of arches and draperies. And the elves are not stately, somber, serious no-funs of Middle Earth. They're actually rather silly, merry, and ridiculous. They tease the dwarves with silly songs as they enter the valley. There is no meeting in Rivendell with Saruman and Galadriel, no discussion of the Necromancer. The dwarves do not sneak off. They stay 14 days, I believe, rest and eat, and go on their merry way refreshed.
There are no orcs or goblins, period, in this section of the book. The company is not attacked by orcs on wargs. As a matter of fact, I don't recall any wargs at all in The Hobbit. All of this dark conflict is put in the movie for one purpose only: to make Peter Jackson's movie more scary, for an older audience, and to make it more similar to his trilogy movies. It robs the movie of the light-hearted fun with which the book delights us.