I know there was various opinions about how successful it was. I think Andrew Adamson at one point thought about skipping Prince Caspian.
I do agree about how they've changed Peter's character. There was even tension between Caspian and Peter in the movie. I've read a trivia that CS Lewis have actually thought about writing about a night raid at Miraz's castle in the book. However, the idea got scraped. They even changed Susan's character to a warrior queen. It made no sense, given her title as "Queen Susan the Gentle." I also wasn't a huge fan of the Caspian and Susan romance. I thought it was a bit forced. I kind of get it's a trending or cultural thing in Hollywood. Though I'm sure that a lot of us are getting tired of a romantic sub-plot being forced into just about every Hollywood production.
There are still impressive things about it. The landscape, while distracting at times, looks really nice. The duel between Peter and Miraz, while intense, was spot on! I think they even got Reepicheep right, as being a valiant mouse! I've also liked what they did with Glozelle, by having him feel conflicted and sympathetic. It kind of flesh out his character as not really being loyal to Miraz. The sadness about the old days being gone was really in depth. However, they cut out the romp with Bacchus and Silenus and the freeing of the school children.
I think there are a lot of things that a new PC adaption, still possibly from Netflix, could approve on. One is not have the tension between Peter and Caspian. I think they should find a way on how to do Peter, "I have not come to take your place but to put you in it." Another is no Caspian and Susan romance. I mean, I would be fine if the girls got more interaction with Caspian than they do in the book. But I think I would like to have Caspian and Susan to have more of a sibling like relationship. Perhaps when he offers the horn back, she can say, "You keep it. Who knows when you need to call for help?" I would also like to see some more sympathetic Telmarines. I think it will count for something if we finally see the romp with Bacchus and Silenus and the freeing of the school children.