Heard good things about this, and they were all true. It would have been kind of neat to come into the movie knowing nothing about the plot, but (alas) in our world, that is not an option.
In fact, if you haven't seen the movie, and you don't know anything about it, I recommend you stop reading right now. As Will Ferrell parodying James Lipton would say: "Go to a place where movies are rented, sold, or seen and rent, buy or see this movie. It is delightful"
Still here? Well, the Abbott family (John Krasinski, Emily Blunt, some kid actors) is trying to survive an alien invasion; they are apparently the last remnants of humanity. The aliens are blind, but hypersensitive to sound, which means the Abbotts have to be, as Elmer Fudd would say, vewy, vewy, quiet.
They don't always succeed at that. And an early scene details the tragic consequences, and causes everyone to not only be scared, but also guilt-ridden for the rest of the movie.
Acting is first-rate, the filmmakers know how to put the scares in. Ending (however) is non-credible, once you think about it for a few seconds. Mouseover if you're inclined: [Mom and daughter invent an impromptu, but effective, anti-alien sonic weapon! Are you telling me nobody else in the entire world thought of that?].