...I was kind of disappointed. Then again, I did have sky-high expectations from the man who directed the awesome LOTR trilogy, the actors and the awesome composer (Howard Shore). I saw this in an unusually big group (7 people) and none of us had seen anything but the LOTR movies or read any of Tolkien's books.
After the end, we all agreed on one thing: it feels like a mashup of Harry Potter, Narnia and Shrek. Aside from the beautiful scenery, there's not much of the LOTR atmosphere: in the first half we have many "closed-off" scenes (in small rooms), while the second half is dedicated mostly to a LOT of scenery and heavily focuses on the backgrounds. And while the LOTR trilogy had this feeling of grandeur, this feels much more pop-ish (lots of pop culture jokes and modern terms that don't feel "right" in a fantasy setting); some of the jokes fell flat and you're required to suspend your disbelief quite a few times. As for the special effects, they were top notch 90% of the time, but there were certain situations where they were obvious and took away from the story (such as the wargs - wolf-like creatures - the orcs were riding).
The 3D takes a bit of getting used to, especially the framerate (48 fps versus the usual 24 fps) and you may get the feeling that the movie is fast-forwarded at times; this depends on the individual: some got used to it, some are bothered by it throughout the whole movie, some don't notice it at all. The music, however, is beautiful, as expected from Howard Shore and, no matter what gripes I have with the movie, I can't stop listening to Song of the Lonely Mountain (no really, I've been listening to it for three hours).
If you've seen LOTR (and love it), here's what to keep in mind in order to fully enjoy this movie:
1. Don't treat it as a prequel to LOTR. It's...different. Very different.
2. From what info I could gather, the book The Hobbit movies (this trilogy) are/will be based on is directed towards children and is much more lighthearted than LOTR.
3. It also has around 300 pages, which Peter Jackson managed to stretch into 3 movies.