First let me say that I have read the book and seen the older movies made for BBC. That said I thought it was a good movie, not particularly a perfect adaptation, but C.S. Lewis' books are very allegorical and I understand that some writers and directors would like to "filter" out the messages Lewis put into his books.
The age range of the Chronicles of Narnia is about 9-12 and the first book, The Lion the Witch and the Wardrobe was released in 1950. One book was release every consecutive year and Voyage of the Dawn Treader was the third so it was 1952 before it was released. This means that even if the reader started reading at 9 years old they would have read the third book as a young adult.
My point I am getting to is that the movie isn't age appropriate. In the book there is real danger, the characters get captured and sold into slavery, they nearly starve in the middle of the ocean, and on top of all that there is a mysterious mist that eats people. As in the other movies there is no blood, except when one of the characters receives a paper cut from a mouse with a dagger and that was a drop. It is scary and the characters in the book are scared, in contrast the movie is very lax like they are visiting their grandmother, not wanting to be there, but silently protesting.
I will not give any spoilers, but a creature in the movie transforms and the way he does is he sheds his skin. I know it may be hard to believe, but I liked how the book explained it. In the book he has to rip the skin off like a snake, in the movie it just disintegrates. I disliked this because it was takes away the whole meaning, because it shows that he had to go through some effort in order to be a better person, a "transformation" if you will. The suspense wasn't there for me. I was there with the characters fighting seas and swordsmen, but I felt little worry that the characters were in any real danger. In a horror movie the way you show the beast is a killer is, somebody gets killed. If the audience isn't showed what the danger is there is none.
I liked the movie, but there are some things I would have liked to change. The characters develop nicely and the elements that were changed in the story did not affect the outcome in the end. Allthough I did not see it in 3D the visuals and CG characters were believable and the giant battle at the end is amazing. Considering my expectations I give it an 8 out of 10.