Well, it makes sense that they're a third of the way through the book given that they're a third of the way through the filmed version. It's just unnecessary to give barely over 100 pages of book (in my edition) an entire lengthy movie. I kind of like that we get to see some more about the Necromancer, because it will be a nice feed-in to Lord of the Rings, but this is a bit too much.

I agree with you in liking the way they handled Bilbo deciding to follow the dwarves. It might be a hasty decision he sometimes regrets, but it is at least his decision 100%. The Tookish aspect of him is stronger than he realizes even at such an early point in the story.