Just saw it for the first time in HFR 3D.
3D Review:
48FPS to me looks like a combination of PAL (25fps European television framerate) and the slowest fast-forward setting on a VCR. So basically like sped-up PAL without the ghosting. Or for a better comparison, it looks like that horrible "Smooth Motion" effect on the new 120/240hz televisions that does the soap-opera look and makes everything look like an episode of COPS, or like it was filmed on a home video camera. Only sped up a little, so it looks even worse.
Like BrightCandle said above, I felt like it was too fast in the beginning (probably the first 10 minutes, it was REALLY distracting), but then got used to it (mostly). HFR was the worst when the camera was moving. On static tripod shots, it actually looked really good. Lots of depth to the 3D, and I didn't forget that it was in 3D like I did when watching Avatar - it always added to the 3D effect in a nice way, instead of becoming invisible as you watched the movie.
Two of the biggest benefits I noticed of HFR was the brightness and focus. I never thought 24FPS 3D was dim, but the brightness is on-par with regular 2D movies in HFR, so that was really nice - everything was really clear. Also your eyes don't have to focus-hunt like they do in standard 3D movies - the focus is crystal-clear, you know exactly where to look. You don't get that slightly smeary blurriness that you get in 24FPS 3D, which was really nice.
I also found that I didn't get any 3D fatigue because I wasn't focus-hunting on a slightly blurry picture - I wear normal glasses under the 3D glasses and this felt like watching a 2D movie, no problems there. So no eyestrain, and definitely no "Hobbit Vomit". My wife, who is fairly sensitive to 3D movies and gets slightly queasy, had zero problems with HFR 3D. So they nailed that.
I think HFR 3D is a step in the right direction, but they still need to work out the bugs. They improved clarity, fatigue, and brightness, but it makes the movie look kinda terrible and distracting. I totally agree again with BrightCandle - I think the 48FPS 3D threw off the acting. I know that Martin Freeman (Bilbo, and Watson!) and Ian McKellen are good actors, but there was something lacking about their performance (and all the rest of the characters), and it might be the missing microexpressions or something.
We are trained to equate the ghostly 24fps with film, and despite its problems, I sure love 24fps. I had a hard time really getting immersed in the movie because it didn't look like a movie due to the framerate. I also felt like a lot of the action scenes lacked impact, and I don't know if that was due to the directing or due to the HFR 3D. I also don't know if the movie had a lame soundscape or if my theater had cruddy speakers, but the music didn't sound as huge & immersive as LOTR - I felt that was very lacking, but it could just be crappy movie theater speakers.
Movie Review:
Pros:
I thought the movie was a lot of fun. I liked the pacing - I could have sat through another 30 minutes or even another hour, whereas with LOTR, I wanted an intermission in the middle. Their focus on the story kept things moving. I liked that it was more lighthearted than LOTR (a bit more fun & not quite as "serious" the whole time). The 3D characters are getting really realistic - Smaug's eye was really cool at the end, and the goblin king was pretty crazy (really wish Gandalf had chopped off that monsterous goiter double-chin, haha). And the fighting scenes weren't endless tireless action fighting - they were a good length without being overly long, and they threw in some interesting stuff to break up the monotony (like the ladder bit during the goblin attack).
Cons:
Because the focus was on the story, I felt like a lot of character development got left on by the wayside. I was really interested to get to know the dwarf troop better. Hopefully we can learn more about them in the next couple of episodes. I honestly wish we had had another hour for impact & character development. I was already on Bilbo's side and I eventually jumped onboard with Thorin, but I wanted to root more for the dwarf troop, and I think getting to know their characters better would have helped with that (like in "Castaway" with Tom Hanks - I nearly cried when Wilson the volleyball sailed away, haha). Because the story felt kind of like it was on a timed track (not a bad thing, because LOTR often feels TOO long), I felt like some of the scenes weren't as impactful as they could have been, and could have used more time for the audience to dig into them.
For example, I think they did a good job in Bilbo's first interaction with Gollum - you really got a chance to meet Gollum as a "new" character, see where he came from at that point in the story, see why Bilbo chose not to kill him when he had the chance, etc. (although maybe a tad too long in this case, lol). In LOTR, I liked the side-story of Merry & Pippin. I would have liked to see more of Fili & Kili, for example, and some of the other interesting-looking dwarfs in the troop.
As GeoSurface said in the OP, shooting in 3D affects your filmmaking decisions. I think that the Hobbit would have been even better shot as a 2D film because they might have had the time & budget for other stuff. Some things felt left out or missing - some of the makeup didn't seem quite right, like they ran out of time to do a really stellar job, and the acting & impact seemed off (although that was probably a result of the HFS 3D), etc. I don't know how much 3D really added to the film, aside from pioneering 48FPS 3D. I think it's a step in the right direction technology-wise (improvements in brightness, focus, etc.), but I don't know if this was the right film to do that in. I would like to see it again in 2D to see how that compares - my wife said it was much more natural & film-like in 2D (the first time she saw it) and she liked it more that way. A lot of people who saw it in 24FPS 3D said the panning was really horrible, like you were on a rollercoaster or something, and that it was stuttery.
Summary:
Fun show, I enjoyed it. Felt like it could have been more impactful story-wise and would have liked to have seen more side-character development, but it was a well-told story that left me wanting to see the next one. Not impressed by HFR 3D; given the choice of 3D, I would see it in standard 24FPS 3D. Given the choice out of all 3, I would have seen it in 2D (unlike Avatar, which I think benefited from the 3D). I chose not to see it in IMAX 3D because we have one of those fake IMAX theaters and our Real 3D DLP theater is way better and almost as big.
Side note: Still wondering why they didn't take the eagles to the mountain in the first place, especially since there weren't any of the mini-dragons from LOTR flying around to stop them...