Okay, so I actually got to see this film today, opening day, rather than having to wait a while until the massive crowds died down a bit (it sucks to be stuck in a bad seat somewhere because they're the only ones left). Normally I give a like/dislike statement and then ramble on about various bits, but this movie is different.
Originally, I was thrilled when they announced that they would be going ahead with The Hobbit as a movie. Naturally I worried about how true they would stay to the book but was not too worried, given that the Lord of the Rings (LotR) trilogy came out quite well. However, the people making The Hobbit clearly decided to take a very different approach and change quite a lot of the story. The main plot points are there, but they have added A LOT and altered still more.Thus I found myself watching a story "based on The Hobbit" rather than a reasonably faithful screen adaptation. I did like that they added a prologue providing background on the dwarf hold in the mountain, the lake town, and the coming of Smaug. That will help viewers new to The Hobbit get settled in before the main story starts.
The dwarves are a mix of cool and clownish. Since The Hobbit was meant to have a less dark and gritty atmosphere than the LotR I can understand putting in some characters for laughs. Some of the dwarves function very much like Merry and Pippin in LotR. However I don't really like when a serious story includes gratuitous comic relief characters, such as Jar-Jar Binks in Star Wars. In addition several of the dwarves were visually ridiculous--while several were more "realistic" in appearance. The difference was jarring. Likewise the wizard Radagast the Brown is mostly played for laughs, in contrast to Ian McKellan's excellent Gandalf the Gray. I really wish they'd picked an R-rated dark and gritty approach or a PG-13 storybook approach and stuck with it throughout.
I was also disappointed in the rather abrupt ending to the film. Given the length of the book they really could have done it in one three-hour film. I now feel that it is in two parts due to a deliberate business decision to add more new stuff in order to pad it out into two films. Oh well. I will go see the second film in the theatre, but I won't buy either part to watch at home.