I've been a huge fan of Narnia since I was a small child, so the making of the movies is extremely exciting for me. And Prince Caspian did not disappoint. It is exciting and adventurous, not to mention often quite humorous. It grips you and forces you to fall in love with the characters. For movie lovers of any age, it is a must.
For lovers of the book, I will say this: some serious dramatic license is taken in the movie. Some of Prince Caspian's history is left out, but only the unessential. And that is understandable because of the differences between movies and books. Many parts of the book are embellished in the film and some are added from scratch. But do not despair. In no way did I think the book was mutilated by the movie.
Susan is developed far more as a character in the movie, something which even die-hard fans may admit was lacking in the book. Peter is a far more intriguing and dynamic character. The added wit of the movie compliments that used in the book. There are a few minor pieces which I would change to be more like the book, or simply because they were unnecessary, but these do not interfere too much with the success of the movie. All in all, though the writers did not stay entirely true to the storyline, they stayed true to the tone.
The most important thing for book fans when viewing this movie is to separate it from their memory of the book. It is an extremely entertaining movie as long as one is not expecting a word-for-word translation.