The full title of this movie is The Chronicles of Narnia: Prince Caspian, but nobody is actually going to say that. It’s a sequel to 2005′s The Lion, the Witch and the Wardroble and the first thing I should warn you about is that if you haven’t seen that movie, or read the book by C.S. Lewis on which it was based, you shouldn’t bother with the sequel. Prince Caspian jumps right into the action, and without that previous exposure you won’t know what is going on, or who the main characters are, or why you should care what happens to them.
On the other hand, if you saw and liked The Lion, the Witch and the Wardrobe (I’m just going to write TLTWTW henceforth) then it’s probably worth seeing the sequel. The spectacular final battle sequence is worth the price of admission by itself.