If you have never read the book, go ahead and see the movie. It's not that bad. It's nowhere near as good as the Lords of the Rings, but it's not bad.
If you've read the book however, be prepared for disappointment. The movie isn't long, only an hour and a half, and in my opinion, could have profited from an extention into a three hour long movie like what was done for the Lord of the Rings. Then maybe it wouldn't feel so much like a short resume of the book.
So much was cut out in fact, that MORE was left out than was put in. When you are cutting out that much, it just isn't worth it to make the movie anymore. You don't get the same sense of character development. What took months to achieve seems to take place in a matter of a few weeks. Many characters are missing or extremely underdeveloped. Whole subplots are missing. Heck, for the sake of the movie, they must have cut out almost 10 chapters in a row at times.
This is just one of those cases where the book is way, way better than the movie.