Short and sweet review: this movie wasn't that great. While the overall plot line stuck to Tolkien's story, mostly, there were large and largely needless re-writes that sucked the charm and wit right out of Jackson's movie. Furthermore, the occasional insertions of bits of the back-story were alright, but after a while they began to overshadow the main plot. As its own story The Hobbit – at least Tolkien's version – stands on its own. There was no need to shape it into a Lord of the Rings prequel for this movie version.
Apart from these re-write problems, the acting was very good, the set design was perfect, and the special effects were top-knotch. They manage to drag it up to 2.5 stars out of 4. It was enjoyable to watch, but it could have been so much more.