This is quite a sparse film that generates tension from not knowing, with just brief glimpses of bad things unfolding elsewhere.
There is enough happening to just about hold interest. It's not too silly. There's some slightly exciting moments. The acting is quite good, although no one is reacting in a way that you'd expect. By the end you don't really care enough about the characters, or the whole of America represented by the film, to be bothered with what happens to them.
I've not read the book but I guess the film is just rendering the book. It's pretty bleak but interesting enough. Not one for the ages.