Short version: Prince Caspian is much better than the first Narnia film.
Let's get straight to the point: If you liked the first Chronicles of Narnia movie, you'll like this one even better. For some reason I never wrote a review of the first one, but if I had I probably would have given it about , a full point lower than Prince Caspian.
On the other hand, if you're a big fan of the book upon which this film is based, you're going to be torn because it deviates heavily from that story. I wouldn't have known that myself, but my daughter re-read the book just recently and found herself pulled in two directions regarding the movie. On its own she thought it was very good, but she was perturbed over the inclusion of entire sequences that never appeared in the book while parts of the original story were completely absent from the film.
Prince Caspian starts right off with a much darker feel than the last film, actually reminding me of a Harry Potter film with the dark castle environment. We witness (in PG fashion) the birth of a child and the announcement to the father (who appears to be in a king, but isn't quite) that he has a son.
The nature of this lord (not a king) becomes immediately apparent when he orders the execution of prince Caspian, who is only saved with the help of his long time professor. Caspian is sent into the woods which legend (and superstition) says is populated by all kinds of scary creatures. Eventually Caspian runs into some denizens of Nania, long thought extinct and calls upon "the kings of old" for help.
Of course the kings of old turn out not to be very old at all but are out intrepid young 'uns from the first film. Peter, the oldest is not happy that they've been away from Narnia for a year and has not adjusted well to life here in the real world. If you recall they lived an entire lifetime in Narnia during the first film and returned at their original ages. Meanwhile Susan, next oldest, is just trying to come to terms with the fact that they'll never return to Narnia and get on with her life.
Once they return they slowly discover that over 1,000 years have passed since they left and things have (obviously) changed dramatically. Unknown to them it will be their task to bring Narnia out of hiding and back to a flourishing civilization.
I thought that Ben Barnes as Prince Caspian did an OK job in the role... adequate, but nothing to write home about. I think the star of the group of four heroes is 12 year old (but much younger looking) Georgie Henley as Lucy. For me the weak point is the most important character, Peter. I feel like there's just something a bit to "vanilla" about William Moseley's performance which takes away from the film. I will say I thought he was more believable and engaging than he was in the last movie, however.
There's a great cast of supporting characters, topped by Peter Dinklage as the diminutive Trumpkin. He's a little guy with a very commanding presence and that's tough to pull off. I also thought Predrag Bjelac played a great villian as Lord Donnon.
For some folks the film may move a bit slow at times, but I thought it was fine - really a lot of character development/growth in this one, and the final battle sequence is really damned cool. On a side note, as I've seen expressed on other sites I was surprised that this received a PG rating. I think it pushed it pretty hard for PG, but despite all the sword fights and battles not a drop of blood (OK, maybe a small cut here and there) was to be seen.
All in all I thought it was quite good, but not stellar. A big improvement over the first and well worth checking out if you're a fan of the first one and/or a parent looking for a grand adventure film you can bring the kids to.
We'll have to see if it does well enough to guarantee another film based on the book series by C.S. Lewis.