Didn't expect this to be quite so unhinged. The poster had me braced for a fairly standard haunted-house riff, and for the first stretch, that's what you get — properly unsettling, with a house full of trick stairs and hidden passages that keeps you guessing where you actually are.
Then somewhere around the middle it gives up on being scary and goes full panto instead. The two leads go so big the whole thing tips into comedy, which I don't think is a flaw so much as a gear change nobody warned you about. There's one reversal early on so brazen I laughed out loud.
The thing is, the plot barely holds together if you look at it straight on — the family setup, the kid living in the walls, none of it survives scrutiny. It moves fast enough that you don't notice at the time, though the back half drags once the house stops being novel and turns into one long chase.
Basically two different films stapled together. Somehow both halves earn their keep, most of the time.
An equal parts absurdist and chilling intertwining of claustrophobic thrills, slapstick comedy and social commentary.