If you don't watch the Science Fiction news pretty carefully you probably didn't know that Disney had dropped out of the Narnia series. Prince Caspian didn't make as much as was hoped and they weren't interested in taking the risk. Only a couple days later 20th Century Fox stepped in and the movie is back on.
I am surprised that Prince Caspian did so poorly. The book is different from The Lion, The Witch and the Wardrobe but I for one really enjoyed it. Perhaps people who didn't read the books were expecting a sequel that took place a few months after the last, but I remember when I read the books being pleasantly surprised when i found out that time passes differently in Narnia.
If you are uncertain if you should watch another of the Narnia series because you disliked Prince Caspian then I would strongly suggest you give it another chance. This movie is far more fantasy friendly.