The biggest issue I had with Prince Caspian as a film was the redefining of characters. The filmmakers abandoned Susan and her character development from the first film; from vocally opposing the battle and "not planning on fighting any witch" to actively participating in an offensive attack on the enemy in PC.

If they wanted to keep Susan the way Lewis wrote her, she would have never joined them in the night raid sequence. At most, she defends, never attacks. Instead, Lucy is the one who opposes the raid. But see, why couldn't the filmmakers have them both oppose it for different reasons? Lucy looks at it as a refusal to trust Aslan, but Susan rejects it for selfish/fearful reasons, echoing what she told Lucy at the campfire, of "finally getting used to the idea of being in England." That would add interesting confrontation.

You bring up a good point, King_Erlian, about not having very many gentle-natured characters in movies anymore. Remember when Peter Jackson and crew almost included Arwen at the battle of Helm's Deep? They wisely abandoned the idea, and that took courage on their part.

I think when it comes down to it, Susan turned into "Warrior Princess" because it was the safe and easy thing to do, an expectation for her to be more modern and current-day. And the Narnia movies are never going to be remembered as anything special when they take such cheap routes.

By the time of Price Caspian, Susan has grown up and been a mature adult queen, could have been married several times, and could have developed fighting skills had she wished. Indeed, if we followed Lewis's published order, by PC we don't know that she hasn't done any at all.
Based on that, it would not be impossible for her to have been an archer who was sometimes part of a battle.
A year after returning to England, Susan is back in Narnia; within a couple of days they are remembering skills and regaining strength. If Susan had been more active in her adult years, taking it on again as a 15 year old is possible (12 -13 in the book ).

After reading HHB we know that she has not been in the battles. So if the writers and producers made her a warrior princess, they either didnt read the other books, or ignoredo them for their own purpose.
Poor Susan- she could never compete with Eowyn!

I'm surprised no one has pointed out that LWW already made the Pevensies older than they were in the book except for Lucy. I would have been more surprised if they weren't teenagers in the PC movie. Did you expect them to recast all the actors?

While I don't agree with the director's reasons for making Susan an action heroine (if I recall them correctly), I don't really see how the story lost a good role model for pacific natured kids. In the book, Susan is actually the most negatively portrayed of the kids. (In the movie, this ended up being Peter. Perhaps this was also due to concerns about gender issues.) I'm not saying that Susan was a bad character in the book. I actually think it's really interesting how she says she believed Lucy saw Aslan but she pretended not to because she was desperate to get out the wood. I might have behaved the same way; I hate hiking against my will. But she seems like she was never intended to be a super positively portrayed character.

In the book, the main problems pretty much were solved by violence, either the Narnians killing the Telmarines or Aslan magically coercing the Telmarines. Susan didn't really do anything to help at the climax. I like the message of their being non-violent solutions but that message was never going to be attached to Prince Caspian.