The Kid Who Would Be King reminds me of the kids movies I watched as a kid, where an actual child comes into possession of something they shouldn't, like a spaceship, or a professional baseball team, or, in this case, King Arthur's enchanted sword Excalibur. Wildly irresponsible behavior and at least one heartfelt exchange with a single parent ensues, end everyone learns a valuable lesson about the value of family and the importance of teamwork. It was great stuff back then and it's fun to see now—although, as with a lot of purely childlike fantasy, it doesn't hang together as well as you'd hope.
Thankfully, writer/director Joe Cornish brings the same sublime toolbox he used for the gleefully anarchic Attack the Block, transforming the stultifyingly bland public spaces of contemporary Britain into a fantastical playground filled with flaming skeleton knights and enchanted undergrowth. The young cast is enthusiastic and charming, and the film takes some welcome shots at the "chosen one" narrative that's infected too much modern YA. Best of all—at least for parents—it manages this feat without product placement, musical numbers, or any characters who are clearly there solely to deliver obnoxious catchphrases.