I saw this movie yesterday. Its interesting for a couple of reasons.
The number one is technically, its visually impressive. The 3-D animation process is probably one of the most lifelike movies every made of this genre.
That said, there is a reason this movie is PG-13. The sex and violence in this movie has a different feel than in a 2-D movie. You see Angelina Jolie in all her beauty nude on the screen. Probably the most we have seen of her since GIA. She is breathtaking as the seductress, even enough that she was taken back by how she looked in the movie.
The storyline is well known as a Norse fantasy tale with dragons and demons. So if you enjoy that genre this movie is a must see. Seeing it in 3d is the reason to spend the extra money to see it in the theater. An enjoyable couple of hours.