Saw this last night in 3D and really liked it. There are quite a few changes from the book but I was mostly okay with them. There's a whole extra villain introduced into the movie that's not in the book and the Dwarves are a little more bad-ass than in the book.
I thought that the higher frame rate was supposed to cut down on motion blur, but I noticed a few placed where the blur was terrible; some of the beginning scenes in Dale, during their run through the Goblin layer in the mountian and one other that I'm forgetting now. Otherwise, I thought the film looked gorgeous and the 3D made some things really pop. Jackson also, IMO, did a good job in letting the 3D enhance things and didn't play it as a gag so he could throw stuff "out" of the screen at you, sort of like how Cameron treated Avatar, but unlike how pretty much everyone else treats it.
There's a decent article over on The Daily Beast pointing out 19 changes from the book to film
. I think the writer is nitpicking on a couple of them, meaning yes, they are changes, but they're so minor I probably wouldn't think to point them out, and I think she missed the point on at least one of them...still a good article, though.