surprisingly fun for adults given it was based on a children's book

Rating: 9/10 (18 December 2012)

Background about my expectations: I am a huge Tolkien fan. I didn't expect to enjoy this movie that much because The Hobbit is a kid's book. I read it when I was 5. Lord of the Rings was written as a sequel to The Hobbit, but for an adult audience because of the amount of time that passed between when Tolkien wrote The Hobbit and when he wrote Lord of the Rings. I only went to see The Hobbit because my best friend took me for a Yule present.
How this movie exceeded my expectations: I enjoyed The Hobbit very much. I was surprised and delighted to see all the cameos by Lord of the Rings characters, which did not appear in the book. Also not in the book, but very welcome for an audience of adult LOTR fans, was the extended storyline about the Necromancer, the Council of the Wise, and the way the movie brought in the story of the Moria orc / dwarf conflict that had been told elsewhere in Tolkien's writings. I loved Radagast. His story had not really been told anywhere in Tolkien's writings, only hinted at, and he was a delightful character that I'm sure appealed to kids as much as he appealed to older Tolkien fans hungry for new Tolkien-y stuff. All of that is stuff that was not in the book, so if I was in "Tolkien book purist mode" instead of "Lord of the Rings fan fiction reader mode" I would have hated it. This movie is not actually The Hobbit, a movie based on the children's book. It's a completely new work intertextually inserted into the story of The Hobbit, much like Pride and Prejudice and Zombies.
Ways the movie stayed true to the book: I was very happy that all the humor and song from the book did appear in the movie. The costumes, props, sets, makeup, etc. looked right for the characters and the story.