What could have been a work of post-modern, self-referential genius became, in the hands of M. Night Shyamalan, a blunt schtick used to repeatedly batter its audience over the head. Armed with his demiurgical impulse, Shyamalan creates a fable waterworld full of mermaid-like creatures that inexplicably sport two legs and no fins or gills. Through a swimming pool he then puts this world in conflict with modern society in the form of a cinder-block apartment building peopled with kooks and led by Paul Giamatti whose stuttering act sounds more like he's in the throes of self-passion rather than self-consciousness.It's not as if there isn't a precedent for movies that have turned even famous fables on their pointy ears, Neil Jordan's The Company of Wolves, for instance. But Shymalan doesn't trust his fable. He portions it out in miserly five-minute scenes via a woman translating for her distrustful mother, appropriatly exotic, i.e. Asian. Yet the rules of the fable world still aren't set. There are mistaken identities and a failed party and an attempt to learn about fables by consulting a movie reviewer. Not to mention that the scenery seems to shape-shift, depending on the needs of the scene. When Paul Giamatti's character needs to be at the pool quickly, his caretaker's bungalow is set poolside. When there needs to be a meadow between his house and the pool, there's the grassy field.
In the end, there are no great lessons to be learned, other than the sign of a bad movie is the number of backstories on which your plot relies. In more adept hands, a movie in which nothing happens that hasn't been expostulated five minutes before could be fascinating. It just wouldn't have been made by Hollywood.