Do watch it...you will be surprised....
Gripping story, even if sci fi isn't your cup of tea
Joseph Gordon-Levitt and Emily Blunt's performances are outstanding, as is the central child actor
Extreme violence, and the violence against children was particularly disturbing to me. It is central to the plot and not gratuitous but still incredibly difficult to watch. I wouldn't rewatch the film for that alone. It's a shame those characters could not have been older--it would still work for the plot without such incredibly disturbing violence.
The secondary characters outside of Daniels really didn't do much. There were also a couple of head-scratching errors that weren't explained and kind of rendered the whole plot meaningless, but I won't spoil them here.
Not exactly a boring movie, but you'll forget about it 5 minutes after it's over.