Hobbit purists may balk at Peter Jackson's interpretation of the story, but the movie is definitely entertaining - though undeniably too long.
Middle Earth doesn't hold a particularly special place in my heart. I liked The Hobbit well enough as a kid, but it never became a favorite for annual rereadings. I later tried getting into Lord of the Rings, but could never get past the section introducing Tom Bombadil; after repeated attempts, I settled for skimming the trilogy for the action-filled parts.
I did enjoy Peter Jackson's The Fellowship of the Ring. Though the second and third films were comparatively underwhelming, I think the casting was done well, loved the scenery, and enjoyed the overall look and feel of the franchise (however: even at the time some of the special effects seemed cheesy to me - especially Treebeard & co. and the battle scenes with the giant elephants). Seeing the movies was like skimming through the books all over again: the action without the dull exposition.
Based on this, my main concern going into The Hobbit was that Jackson's conceptualization of the book as a trilogy (with the first film already 170 minutes long) would make the films proportionately more dull.
This was not the case. I liked the opening scene, wasn't disappointed by the dwarves coming to dinner at Bilbo's place (my favorite scene from the book), and liked the rest...well enough.
It's probably because I'm not a purist concerning the book, but Jackson's artistic liberties with The Hobbit - expanding the source material through Tolkien's supplements and wholly new creations - didn't bother me. I was, however, increasinly bemused by how diffuse the film became. Tasha Robinson at the A. V. Club argued that this is because the story "was already resolved in the Rings movies, which dissolves any sense of stakes." The flaw in this theory is that it could be applied to any movie prequel, or even to any film based on a well-known novel (also, does this mean that rewatching films or rereading books is pointless?).
For me, it comes down to the number of dramatic "there's no way out of here" climaxes. By the time the big one (for this film) comes around, the crew had already been through so much drama that it was difficult to muster "hey, this is the main climax" enthusiasm. So the movie's shortcomings are a by-product of its overall length.
Related to this, the sheer amount of deus ex machinae also became overwhelming. Gandalf's magic, combined with help from his magical friends (elves, giant eagles) gets the gang out of various hopeless situations, and the knowledge that he can do magic makes a lot of the danger seem less consequential.
The casting, in turn, is well done once more. Martin Freeman (who has clearly made a career of playing deceptively quasi-wimpy nice guys with hidden strengths) makes a perfect Bilbo; and I appreciate that so many of the other actors resumed their roles. Though I don't think that the movie's way of tying the beginning of Jackson's Fellowship to this film adds anything besides showing that Elijah Wood can still pass as a teenager with appropriate makeup and lighting (so if you want to talk about editing, that scene would be good place to start).
However: since there's no need for historical accuracy in this type of fantasy, I don't understand why some of the more problematic elements of the book couldn't have been revised for the film.
For instance, all the dwarves in the company were (as far as I could see) white and male. Unlike Time magazine which bemoans a complete lack of female characters save for Galadriel, I did notice some lady dwarves running from Smaug in the opening scene, so it's marginalization rather than complete absence. Still, would it have hurt the film to make some dwarves in the company more diverse?
Similarly, Tolkien's depiction of the dwarves - which he himself said was inspired by Jewish history just as the dwarf language is based on semitic languages - has its issues. The main parallels are fairly benign: dwarves are a people wandering the earth without a home after the cultural and economic center of their civilization was destroyed. However, their destructive lust for gold is a bit ickier. Not like the movie could have changed that without significantly impacting the plot, but giving the dwarves' humungous prosthetic noses seem a bit excessive. The only dwarves without prosthetics are those designated as eye candy - who are close relatives of royal lineage.
The visual differences between goblins, orcs, and trolls weren't drawn all that well, but goblin-town was an awesome feat of the imagination (and CGI). Guillemero del Toro (originally slated as director before he had to bow out) is still listed as a producer and co-screenwriter, and goblinburg was reminiscent of the worlds he created for Pan's Labyrinth and Hellboy 2. I especially liked the touch of the little goblin who took a cable car-like contraption to get a message to the orcs.
We watched the movie in 2-D, but at 48 frames per second. This was a huge distraction for me at the action-filled beginning with all its sweeping battle shots - they were dizzying and I felt my brain just wasn't able to process the speed, so it was pretty much lost on me. Time suggests that eventually your eyes get used to it, which - if true - is the reason it stopped bothering me about 20 minutes into the movie. I liked the increased clarity in the sweeping shots, but it also made the CGI look more artificial in some scenes (rabbits) and made slight visual continuity errors stand out quite jarringly.
All photos are from the official movie website.