Short answer: atmospheric dark fantasy with some memorable scenes and Scarlett Johansson naked, but slow and lacking in story. Cautiously recommended, as long as you’re prepared to be kinda bored.
Longer thoughts below — spoilers ahead.
I have a theory about art movies — that they are boring on purpose, and boring in a particular way, in order to signal “this is an art movie.” So they always have plenty of long suspended moments, usually well-filmed, during which there is no dialog and nothing in particular is happening. Professional cinema reviewers never seem to mind, either — it’s rare for glacial pace and lack of incident to be singled out as flaws.
It makes me feel like a cretin sometimes, to be sitting there watching a movie — this one, or Beasts of the Southern Wild, or Brokeback Mountain, or Martha Marcy May Marlene — and be thinking, “this is good, but it could be less boring.” It’s almost like being able to put up with boring art, without calling it out for being dull, is recognized as a signal that you are a person with taste. You are a person who is not bored by art movies. You are better than those restless yahoos squirming in the back, who just came because they wanted to see Scarlett Johansson take her clothes off, and are whispering to each other about how horrible this movie is and they should have seen the new Captain America instead.
Really, I think I wouldn’t have been bored at all if it had been a little more up front with the story. There’s a fine line between “enigmatic” and “completely opaque” and I think this movie falls too much on the opaque side. But that’s another way of signaling that we’re watching an art film, isn’t it? Make the audience work to figure out what’s going on, and give them lots of time to think really hard about it.
Every review of this movie calls Scarlett Johansson’s character an “alien,” but they must be getting that from the press kit or something, because there is actually nothing in the movie to tell you what kind of inhuman predator she is. She lures men into a puddle of black goo, and her true form is person-shaped black goo, and she has a silent protector/boss/cleanup man who rides around on a motorcycle — none of that signals “alien” to me. If it’s important to know that she’s an alien, in movie terms, we don’t. She could be some weird predatory selkie. (The movie is set in northern Scotland. I wasn’t sure if the frequently unintelligible accents were intentionally thematic.)
The movie has only one real plot turn, about halfway through, when she lures a severely disfigured man back to her place, and fails to finish him off. We see him start heading into the black goo, and then later we see him running naked across a field. After that point, she no longer picks up any victims and her body seems to be breaking down — she’s clumsy, unable to communicate, and eventually literally disintegrates as the Scarlett Johansson outer shell sloughs off to reveal the creature underneath. She shows signs of going native, ordering a piece of cake that she literally can’t eat, displaying fear, and trying to have sex (which ultimately fails, because, it is strongly implied, she lacks an opening in the appropriate place.)
Now, the scene where she picks up the disfigured man is really lovely. Her script is exactly the same as it always is — she displays no awareness at all that he’s not the usual average-looking guy unable to believe he’s getting hit on by somebody who looks like Scarlett Johansson. His wary disbelief, and ultimate acceptance that it must be a dream, is genuinely touching. But why doesn’t he get absorbed by the goo? I’ve seen several reviews that assert she takes pity on him and lets him go, but there’s not a moment in the film where we see her make that decision. So I was convinced that it was just the mechanism breaking down somehow. If the breakdown is caused by a change in her — an infection of humanity, perhaps — that’s a pretty important thing that the movie should actually have shown us.
Still, as I indicated above, I cautiously recommend this movie, if you’re willing to put up with being a bit bored. Many of the scenes are really memorable and creepy, and the score is fantastic. It’s an interesting movie to have seen, even if the act of sitting through it in the first place is sometimes dull.