Under the Skin is an artful, thoughtful, look at an unexpected moment of self discovery. The pace is very deliberate, yet slow.. with, what I would say is, a good payoff in the end. Scarlett Johansson did a great job in her, nameless, role.
There is no way to review this movie, without some major spoilers.. so Spoilers it is!
An alien team has come to earth with the apparent mission to process humans, into some sort of food source.. this is not fully explained, but is eluded to in a brief scene. A female of the team lures human males back to a small house, where they are seduced to complacency, and are consumed by some sort of dark water, which breaks them down from the inside out, leaving just a husk of their skin.
The moment of self awareness and discovery comes when the female takes pity on a deformed man, and allows him to escape. From this point on, she begins to notice small, everyday, things – observing more than just what it takes to lure men away, she experiences kindness, self-sacrifice.
She tries to understand these humans, unsuccessfully trying to eat human food.. and even attempts to make an emotional attachment, and engage in sexual intimacy.. but, her real body cannot handle these things, and it brings more frustration than anything else.. along with a new sense of fear.
As stated above, Scarlett did a great job. The movie is well done, artful and well thought out, with a satisfying final reveal. Unfortunately, this also led to the pace being very slow. And that may put some people off.
