It's an animated movie, based on a story by Diana Coles called "The Clever Princess". It's a feminist subversion of fairy tale tropes, but in a slow, unexciting, Ghibli sort of way. It doesn't have jokes or banter. Disney's more fun, but this is still quite an interesting experience.
Princess Arete is a little girl who thinks princesses are boring and unproductive. She lives at the top of a tower and isn't allowed to go anywhere or make anything. She likes books, but unfortunately this is a medieval world where books are rare and valuable. She has, though, discovered the castle's secret passages and regularly uses them to sneak out of the castle and explore the town. (No one ever recognises her. As a princess in a tower, she's an anonymous thing that exists only a marriage prospect, not a person. Marry Arete and you'll become next in line to the throne! This is historically authentic, but to modern eyes gives us the creepy scene of an adult knight sneaking into the tower to woo a pre-pubescent. He professes his ardent love, although of course what he's in love with is the idea of the crown.)
The film's first 15 minutes are quite fun and show us Arete methodically busting the restrictions of her life. She has no friends or confidents. She just does everything for herself, silently and stoically.
After that, it's demonstrated that Arete officially exists only as a marriage prospect. Her nearly mute royal dad sends knights out to win her with heroic deeds, which in practice means killing and stealing. They're stupid and pleased with themselves, whereas Arete is sharp as a knife. Seriously, that girl is clever.
Then, a wizard appears at court.
There's a ring that can grant three wishes. There's a princess in a dungeon, waiting passively for a knight to rescue her. (This is the slowest stretch of the film, because a spell has been cast on Arete to turn her into the fairy tale stereotype of her role. The real Arete is trapped inside a pretty but bovine body that's not hers, rendering her incapable of initiative or action.) There are frog transformations. Theoretically, this is as fairy-tale as you can get... but, in practice, it couldn't be further away from them. (It's even further from Disney, mind you, being uninterested in jokes, banter or fun. It's portraying the Middle Ages as drab and narrow-minded. It's into historical authenticity and letting scenes play out at a distance, in their own time.)
In its way, though, it's pretty cool. Arete is very likeable, in her stoic, unexpressive way. She does good things, demurely demolishes idiots and achieves tasks that men thought were impossible. (I particularly liked the simplicity of how she steals back that book and how very, very stupid the men involved are not to catch her.) I also love the world created by the animators, with a ton of visual research and specific costumes, architecture, etc. from admittedly a range of centuries. This understated film won't appeal to a lot of children (probably most), but there will be some who love it and I wouldn't really call it a children's film anyway. If what I've described sounds like your thing, it's worth a look.