Prince Caspian - Are sequels always better or worse than their prequels?

I went to see The Chronicles of Narnia: Prince Caspian yesterday. Here's my overall review of the new Narnia sequel.

The visual effects were probably a little more advanced than the first movie's, but one of the disappointing things was that there were a lot of tense, dramatic moments, building to a climax. Or stupid stunts like when Susan loses her balance and Trumpkin grabs her arm, but can't hold on and lets go. Then she falls about two yards onto a grassy ledge below. I was sitting in the theater thinking "What the heck?" And what's with the big castle raid sequence? It wasn't in the book, though the filmmakers can be forgiven, since it was fairly awesome. And neither was the White Witch part. In the book, Nikabrik, the Hag, and the Werewolf do try to convince Caspian to unite with the dark powers, but I believe Jadis played no part, since she was dead. I'll admit that Skandar Keynes gave a better performance as Edmund, and Georgie Henley might have lost a little weight, but I think Ben Barnes is a little old to play Caspian.

Overall, I'd give the movie a 7 out of 10. Which is a "pretty good" rating. If you're a fan of Narnia, see it. If you're a Lewis purist, don't see it. I am looking forward to Dawn Treader and Silver Chair, hoping they'll be a little better.