I went this morning with my oldest son and onliest daughter to see Prince Caspian. I thoroughly enjoyed it. It was a bit long for my 5-year old daughter though she did warm my heart by continuously -- and anxiously -- asking when the "war scenes" were coming. My 8-year old son loved it. I doubt he thoroughly appreciated the themes of justice, courage, redemption, et al., but CS Lewis probably wouldn't have expected him to and besides all that; most of the time those things are there for those who are looking -- like the Christian themes.
I noticed a couple of reviewers were worried about the watering-down of Lewis' Christian themes. Perhaps a bit, especially with the ham-handed "romance" between Caspian and Susan. Susan -- in the book -- is more devoted to Aslan than any puppy-love, but it was a few jokes sprinkled throughout the film and a brief scene at the end and it all blew over. "No harm no foul" as they say in basketball. Aslan also made few appearances and it looks like the director resisted the temptation to turn him into a plush-toy. There were moments where he could've been trivialized, but the director resisted nicely enough. Eddie Izzard had some nice moments and Peter Dinklage is out and out a fine actor.
I highly recommend it. Edmund and Lucy especially shine and the action scenes -- including a single combat scene -- were really well done.