I don't like licensed games... but this is actually a very playable and visually attractive game, with game play elements that are almost explicitly a tribute to Zelda II for the NES, but updated to make full use of the DS, and with lots of Adventure Time specific elements.
Inventory management is a fun mechanic, though both the d-pad control scheme for inventory selection and the touchscreen controls are a little fiddly when trying to use items in combat--this just forces you to know where your items are in the inventory box. Sidescrolling stages have great movement and combat mechanics and never feel like generic licensed game trash, though hit boxes are definitely pretty chunky. Large numbers of single use items that give you special abilities mean that combat can be varied and strategic. High replay value.
Great attention to detail and loving devotion to the weirdness and art style of early Adventure Time. Probably targeted fairly young with a shallow difficulty curve and short length, but very playable. Recommend for fans of Minish Cap, Mario and Luigi, and similar games.