For all that the flat, ill-lit imagery bothered me for most of the whole running time (if I am being honest, the first two shots in the film are very strong arguments in favor of the possibilities of the iPhone used well), that's not the film's only flaw, nor its gravest. What really trips up Unsane is how rambling and unfocused it as. The film is Soderbergh's first horror movie - though he has made thrillers - and it has a perfectly serviceable plot concept for its genre: Sawyer Valentini (Claire Foy) has popped over to the local psychiatric hospital for a 30-minute session to discuss her feelings of trauma related to the stalker who chased her out of Massachusetts (she has just started up a new life in Pennsylvania). Unexpectedly, and for no apparent reason than her offhand mention of having entertained suicidal thoughts at points in the past, Sawyer ends up committed for 24 hours, and those 24 hours turn into seven days. So a good meat-and-potatoes "trapped in the nuthouse!" thriller, and then screenwriters Jonathan Bernstein & James Greer add a wrinkle: one of the orderlies at the hospital, George Shaw (Joshua Leonard), is either Sawyer's stalker David Strine hiding under a new name, or else he looks exactly like the man. Either way, it's enough to get Sawyer worked up into a lather that only convinces the doctors, staff, and other patients that she really is as crazy as all that.
The stuff of a perfectly fine shlocky shocker, but as tends to happen when Real Filmmakers put on their wading bits to wallow in the muck, Unsane doesn't want to be schlock, and this is where many of its problems come in. Generally speaking, we could say that the film has two ideas on its mind: first, it wants to be an indictment of the for-profit medical industry (making it a cousin to Soderbergh's 2013 Side Effects, made before he retired), with fellow patient Nate (Jay Pharaoh, by leaps and bounds the best thing about the movie) suggesting that the hospital is basically just a front for bilking insurance companies. Second, it's attempting to depict the feeling of terrible loneliness and constant tension felt by a woman at the mercy of a ravenous male id, in a world with no support systems for people in her position, and an endless litany of people doubting or openly mocking her fear.
That's already enough to get us in trouble: while in principle it should be possible to marry these two themes, in practice it asks too much of the movie, and it deals with this largely by giving up on the critique of the medical industry the moment it starts to require the film to delve into it any deeper than saying "insurance companies! Yuck!" a couple of times. That means, among other things, that the film leaves itself with a full bouquet of plot holes, of which the most niggling is "but if this hospital keeps abducting people for a week at a time to rob their insurance companies, how have they not been sued, like, dozens of times?" And if the film was content to merely barge on through, being a grimy little shithole of a genre film, perhaps this and all the other plausibility questions wouldn't matter: but this film wants to Say Something, and it really can't do so successfully when it commits such grand-scale intellectual cheats on the very Thing about which it has something to Say.
Without going into it too much, but there are spoilers coming, though ones that any halfway attentive viewer could predict, the problem gets even worse at the end, when the film throws up its hands and goes all-in on becoming a slasher movie. Like, all-in. Teleporting killer and everything. And this is somehow worse than all the rest, because for a film that wants to seriously diagnose how our society fails the victims of stalking, and to examine the psychological state of a victim of stalking, for that film to turn its stalker into an implacable movie monster is just outrageously tacky. Part of the film's conceit, and a major part, is that David Strine is horrifyingly pedestrian, even pathetic, and that makes him all the more threatening, because of how easy it is not to notice the psychosis brewing underneath. Making him Jason Voorhees is a crass tonal error.
Though it does point us back to where I started: this could have been a perfectly fine shlock horror film. Maybe even a very good shlock horror film. Foy is quite good in a part that limits being much better, snarling and peevish and irritably clipped in her line deliveries (her slightly audible difficulty with an American accent actually helps here: it causes her to bite down on her dialogue, as it were, which sharpen's the character's unlikable annoyance). There's always something bracing about horror films that present a tetchy, at times unsympathetic protagonist, and then manipulate us into having sympathy for her anyway, and on that front, Unsane works rather well. It also benefits from Soderbergh's editing (as usually, under the name "Mary Ann Bernard"), which sometimes eschews continuity and not always in places we can expect it, leaving a slightly unreal, difficult-to-follow feeling in the scenes that maps onto Sawyer's nervousness at the Kafkaesque bureaucratic nightmare she's stumbled into.
There's a fine thriller hiding in this movie's bones, then; it simply isn't the film that was actually made. Unsane is too busy and messy for its own good, either as a genre film or as a message picture, and when both of those things are taken away, I'm not sure what's left. Soderbergh's continued experiments are for the good of himself and all of us, but I am much happier when the experiments end in success; Unsane is interesting, but hung up on a cinematography gimmick that never comes within a mile of justifying itself, and too ramshackle as a script to work in spite of that gimmick.