Since I've never read the Hobbit, I wasn't bothered too much by any deviation therefrom, but I do have to admit I think we could have had a much tighter, shorter movie and still gotten everything we needed from it.
As for Bilbo's OOC bravery, since I didn't know it was OOC, I didn't mind it. And we saw that Bilbo was just as surprised that he achieved some of what he intended. The part I did feel was true to character was his slyness in dealing with Gollum and concealing the ring from Gandalf. But I only know that from the LotR trilogy.
I felt that the underground scene with the Goblins was waaaaay to long and the way the dwarfs all survived falling and falling and falling really irritated me. Physics does not work like that.
The same with Radagast's rabbit/warg chase. Another scene that would have benefited from some judicious pruning, maybe completely.
And as much as I think Thorin is pretty darn hot for a dwarf, I really didn't need all the yearning, hair flowing Fabio-like, riding the prow of the Titanic shots we got of him.
As it is, while I did enjoy the movie quite a bit, as I like a lot of action in my movies, I would have been nearly as happy to sit for 2-1/2 hours just looking at the scenery, because New Zealand is fucking gorgeous.
And also, for those of you who saw the 9-minute preview of Star Trek Into Darkness, my friends and I have all concluded that the reboot series is going to be known for the gratuitous shots of the prominent display of Pinecock (clothed) vs. Shatnerchest (bared). For those of us who enjoy these kinds of things, we have a new mantra, "all hail JJ's costume department."