Plankton: The Movie gives SpongeBob's longtime opponent a welcome turn in the spotlight. His grand ambitions and self-pity make entertaining material, though the result still feels more like an extended episode than a fully independent feature.
Karen is tired of her husband's failures and decides to take control herself, including a bid for world domination. Plankton has to become an unlikely hero and stop her, with SpongeBob and the Gal Pals helping.
The absurdity of Bikini Bottom remains intact. Different animation styles and wild, sometimes psychedelic passages supply creative images. The computer-animated look can nevertheless feel too smooth, losing some of the charm of the series' traditional two-dimensional style.
Plankton and Karen's relationship is the strongest addition. Power games and mutual dependence give their marriage problems surprising nuance for this universe, without turning the film solemn. Karen gets more room, and the familiar voice performances keep the characters lively.
The plotting is predictable. Supporting favorites such as Squidward and Mr. Krabs have limited opportunities, which reduces the variety.
Fans of SpongeBob's humor should enjoy the chaos and the shift in perspective. For me, the relationship brings fresh energy to a familiar world, even if the bigger cinematic experience ends up smaller than the premise suggests.