Personally... I LOVED THIS MOVIE, but that's just my opinion. Here is a few things i have to say about it.
~ I heard that the book doesn't actually have a big chase plot with Azog(In my opinion the best character XD). So if they went with book, it would not have been as entertaining.(If im wrong please correct me.
~As said before, a movie is a whole different medium then books, you cant just have Bilbo going on a journey, without giving a bit of story. Not only would that have been boring, but then people who haven't read the book would be clueless.
~Peter Jackson(In my opinion) is also a very great director, one of my favorites. He directed all the Lord of The Rings movies, so he knew what he was getting into.
~You have to give credit to this movie, it was great! The special effects were superb. the acting was great, and you begin to know the characters. I feel like Azog should have been in it more, but hopefully he will be in the 3rd movie.
~Also look on youtube for Peter Jackson's channel. He has all these really awesome behind the scenes, that are really cool.
~Toxic