The Hobbit was always going to have the inescapable problem of being compared to the Lord of the Rings films, and so the creators of this new film had an important decision to make about how they felt the stories should be presented, both in style and in terms of the solidity of their connection. It would have been perfectly possible to hide the overt links between the two sagas, presenting this story in its own right without explicit reference to the familiar scenes to follow. The links would have been there for those willing to look for them, but could have given the prequel more room to find its own style, rather than, as the filmmakers have decided to do, make the connection a part of the story, giving the viewer no doubt that this is intended to form part of a single, larger story.
While this decision perhaps allows for less background to be given (though I would be interested to hear the impression of someone who hadn't seen any of Jackson's previous fantasy epics), the film suffers from the subtle difference in tone between the stories. While Lord of the Rings is (and feels like) a sprawling epic, with huge sacrifices being made in the pursuit of a greater good, The Hobbit seems closer to a fantasy adventure film. More Indiana Jones than The Godfather, maybe. If you disagree with this, ask yourself whether the sequence with the dwarfs and the dishes would have made it into any of the Lord of the Rings films. This is not to imply that the film is in any way "kiddie", but rather that the characters always feel in "peril" rather than "danger". Perhaps this is a subtle distinction (and indeed, perhaps one true only within the confines of my head), but the absence of genuine concern for the characters' safety leads to some of the more extreme action sequences feeling almost comic, rather than thrilling. Gandalf in particular shouts "Run away" one too many times to avoid a possibly slightly unfair comparison to Monty Python and the Holy Grail.
Spreading the action across three films is a decision that has been much-discussed, and I will reserve judgement until I see the other installments, but my initial impression is that the films are going to be more satisfying as a single 9-hour marathon than as individual works. There are so many characters in the main party that it is difficult to get beyond introductions and into character development. Part of this is a natual problem with having a large number of similar-looking, similarly-named characters (and part of me wonders whether I will remember the individual roles and eccentricities of each dwarf come the sequels), but part of it is due to the decision to only tell a third of the story in this film.
As far as the execution of the movie goes, it's everything I would expect from Jackson and from a modern high-budget production. The visuals are clean, convincing and rarely get in the way, while the performances are strong, with Sir Ian McKellen in particular able to add more layers to his portrayal of Gandalf than was possible in Lord of the Rings, since the character has more of an active role here. Richard Armitage also does well enough as Thorin Oakenshield; a sort of dwarfish Viggo Mortensen: two thirds brooding beardily to one third hitting people with metal. Martin Freeman trundles along effectively enough as Bilbo, though I'm more interested to see how his character develops in the second and third films, and there maybe is not enough made of his internal conflict over whether to continue with his adventure, or return home.
Two things particularly stood out to me: Thorin's song (Over the Misty Mountains cold/To dungeons deep and caverns old), which was a note of true solemnity and seriousness, and perfectly captured the isolation of the dwarfs and the anticipation of the adventure to come; and the depiction of Gollum, the encounter between him and Bilbo is fantastically minimlist and (particularly towards the start of their interaction) Gollum appears as a genuinely dangerous and fearsome opponent.
Overall, I was not disappointed by the film (though I will not be seeing the next two in 3D, which added nothing but distraction), and am looking forward to the sequels, but I fear that the filmmakers may have made a rod for their own backs in the tight coupling between the two franchises.