I used to be into the books in a big way, including The Silmarillion, but that was a decade or more ago. I should have re-read the book before I see the movie to be able to better compare the two (because I like doing shit like that, not because a movie can't be good on its own merits).
And I agree, I was disheartened when I heard it was going to be a trilogy. Nothing for it but to hope it rocks I suppose.
Well I saw it. It's long (no surprise there), and there's a lot of filler, like PhoenixDown said. Some I felt could have been omitted, but hey it's a Peter Jackson Tolkien film, they probably left a lot on the cutting room floor they're saving for the first blu ray edition. I remember most of what they added from other JRRT material Radagast the Brown, the Necromancer and Azog the Desecrator!!!! .
The tone is lighter and some of the comedy is more slapstick, but I felt they caught the spirit of the book very well as The Hobbit was much lighter than the LOTR trilogy in literature. A lot of noticeable CG is used, but I thought it was mostly done well. The Gollum scenes are absolutely spot on and brilliant. Lots of scenery pron. The Dwarves are great. Big battle scenes. Dragon teasers. I had not heard of the framerate controversy and didn't notice it, but I saw the regular version (not 3D) so don't even know if that version is filmed at 48fps.
All in all I loved it. I've seen a lot of hate from critics but I don't get it...then again I guess I'm a bit biased. My biggest fear was that this was going to be a Phantom Menace but those fears are allayed. Great movie. A realistic 8/10 for the content and an enthusiastic 9.5 out of 10 because I'm a fanboy and OMG TEH HOBBIT AND IT DOESN'T SUCK IT'S TEH EPIC