Shyamalan's thriller has a strong cast and an initially riveting concept, but it's uneven, and most of the best parts are revealed in the trailer. The performances are serviceable -- particularly Wolff, who's become an expert at the emotional range necessary for creepy horror/psychological thrillers. McKenzie is also notably good at portraying someone who's aged too quickly and is having trouble processing all of her complicated feelings. The adults range in effectiveness, with the striking Pierre (who's excellent in The Underground Railroad) having little to do as the confused and quiet rapper, Sewell chewing up the scenery as an arrogant surgeon, and Bernal and Krieps trying to telegraph how a marriage on the rocks would react when faced with an unthinkable crisis. Stand-outs include Leung and Amuka-Bird, who play the story's sole likable and stable couple.
As in all of his films, Shyamalan also cast himself in a notable, more-than-cameo role, and, while it was predictable, he should have given himself an even smaller part. The twists here, once the titular premise is revealed, are underwhelming (and one is as obvious as Chekhov's gun). There's no gasp-worthy Sixth Sense or The Others moment, which is fine, but the "aha!" doesn't even matter much, because audiences may no longer be invested in the outcome. The best, freakiest parts of the movie rely mostly on the kids' accelerated growth, along with the physiological abnormalities that different characters face while aging a lot in one day (not a spoiler; it's right there in the title). Old ranks somewhere in the bottom half of Shyamalan's filmography, but even so it's worth a look -- if only to see the kids fast-forward into teens.