I have heard it has not got the best reviews from folks though. Tim Seca on Screen Scene was not very kind to the picture for example. I don't want to sound like a fan boy or an apologist but I don't get it. The action is what we have come to expect from the Lord of the Rings series. The story is a bit lighter in tone, but this seems right as The Hobbit was a kids book and LOTR an adult series or novels. Yes the movie has been stretched but this in general has been to include some sections of LOTR that clarified what was happening in the hobbit. The idea that Gandalf is motivated to remove the threat of Smaug aligning with Sauron in the future make his actions more understandable.
Some of the things I really enjoyed were the references to the book material and even outside material. The wizards are mentioned in passing as Ishtari and you hear a reference to spawn of ungoliant. It felt like there were really nods to the Silmarillion. Oddly enough there were actually a couple of nods to War Hammer as well. One of the Dwarves in a battle flash back sports a Mohawk which can only be a reference to the Dwarves of Games Workshop. Also one of the trolls seems inspired by the troll kingdoms butcher. Even the dish washing song seems to use the melody of the old Rakin Bass cartoon. They appear to have gone out of their way make fans happy.
Some of the weird was the stuff with Azog. This is a spoiler so stop if you care. Azog is from an appendix of an appendix of the lord of the ring. He was killed by Dain in the book. He has been reworked to be hunting the Dwarves. It sort of works to give a dramatic arch and provides some logic to the events of the story. I don't know if I am fond of this change it works and doesn't. This leads a bit to what I think is going to be most peoples problem with the movie. In the lord of the rings things are happening and the characters more or less decide to get involved. There is a pretty logical flow for everything. The company could have been on their way to Gondor from Rohan. They really didn't have to say for that fight but in doing so they assured their support in the war. Here events often happen, this is the nature of The Hobbit being a kids book. There is a suspension of belief that is granted in the story. I don't know if the movie benefits from this, I would have worked to explain things more. The goblins in the mountains could have been said to specifically been trying to trap the Dwarves because of Azogs price. Also the mountain giants bit didn't work for me.
What do you get in the movie? Well it starts just before the Lord of the Rings actually. Most is taken to be a retelling of the events. It starts where the book starts and goes until the eagles have saved the company. This sort of worked for me. It's not the dramatic ending of The Fellowship but it gives a since of much more to go and relative completion of what has happened. Alas I screwed up my tickets and saw it in 25 frames per sec without 3d. I need to see it in 48 frames.