Peter Jackson did 'exactly' what I had wished he had done with the LOTR trilogy... took 1 book and split it into enough story for 3 movies. Having read all the books a few dozen (yes, dozen) times each over the years, I knew there was enough good material to make 3 films out of each book, and I am pleased Peter Jackson finally did so.
The casting was good, and the actors reminded me very much of how I saw the characters in my head while reading the book. While there were small, sometimes very subtle differences between the book and the film, they in no way detracted from my enjoyment of The Hobbit. If Jackson strayed somewhat from the letter of the law, he certainly captured the spirit of Tolkien's work beautifully.
Overall, I think The Hobbit: An Unexpected Journey is a 'MUST GO' for longtime fans and anyone new to Tolkien's work.