I went to see it yesterday and I was a bit disappointed.
I thought it would be funnier than it was.
Like others have said, it was a very distilled version of the book and I think it took from a couple of the later books but I may be wrong about that.
I don't care how well a movie sticks to a book, so that's not why I was disappointed.
I just thught the movie should have been funnier and wittier than it was.