Hard core Tolkien fans tend to prefer LotR to "The Hobbit", because the latter work is ultimately a children's book, and has a LOT of flaky, fluffy stuff that makes it hard to take seriously, even though it is ultimately a better told story than LotR. But no one reads Tolkien for the story stucture...
Peter Jackson approached "The Hobbit" with two conflicting goals: To extend the fantasy epic of LotR backwards, and to actually tell the story in the book. This produces a lot of odd stuff, Radagast's incredibly flaky whole cloth insertion chief among them. But one can't say the Radagast interlude violates the SPIRIT of the book, because it does NOT. It is, however, dissonant with LotR. This comes with the territory.
In the end, "The Hobbit" is three hours back in Middle Earth, and if you love the place, you will enjoy being there again. On the other hand, when a 300 page book is inflated into nine hours of film, there is going to be bloat, and there are going to be pacing problems, and there are.
Martin Freeman is perfect as Bilbo, Ian McKellan is perfect as always, Richard Armitage does well with Thorin, and I want Aidan Turner's Kili to have a spin off series all his own (and it breaks my heart to know it will never happen).
All told, a good but not great movie.
The 48 frame 3D camera sees everything better than the human eye does, and puts it all on the screen. This means that when it sees real things (the Bag End interiors, and most of the landscapes), they acquire an uncanny hyper-real character that some find disquieting. It also means that when the camera sees sets made of plaster, plastic, and paint that are meant to look like other things (cave interiors, mostly) they look like plastic, plaster, and paint. Plastic weapon mockups LOOK like plastic mock-ups. Most of the CGI creatures (with the notable exception of Gollum, who is REAL) come off significantly worse in 48/3. For the most part, the industry is NOT ready for this tech, though nature photographers should embrace it whole-heartedly.
One interesting note: 3D has always given me a bit of eyestrain; I get the impression that my eyes, and the relevant parts of my brain, are working overtime to process the slightly discordant sensations of process 3D. I got NONE of that with this film; even the cheesy bits rolled through my eyes effortlessly. A brief discussion with other patrons after the showing confirmed that this effect was not unique to me. I could ALMOST learn to like 3D under these circumstances.