This is a movie about a poor woman who suffers from agoraphobia. She is in a lovely old house with her brother, and she gets meals delivered to her every day, so she doesn't have to go outside. Her brother is dying, and he is pretty much the last person she has ties to in the world. Really, the only other person she interacts with is the delivery boy who brings her the meals they eat and - more recently - the lawyer who is helping her brother sort out his final wishes.
When the time comes that her brother dies, she quite predictably cannot face going outside, so she misses the funeral. It is at this pivotal point that some evil bad guys break into the house (assuming everyone has gone to the funeral) to try to steal what they assume is a lot of money left by the very wealthy brother. That leaves her trapped inside the house with these thugs. And that is when the movie gets interesting.
This movie creates interesting where that Keanu movie failed - with the interaction and the motivations of the people involved within the house. The fact that the criminals have varied motivations is pretty wrote, though. You have the leader who has anger issues, the follower who doesn't really want to hurt anyone, and the guy who is a wild card who just seems to like destruction. Nothing out of the ordinary from the criminals perspective.
The victim reminds me somewhat of the woman from You're Next in that the movie is entirely based on her character, and that is the interesting thing. She's not what you expect, she's not what the attackers expect, and she makes the whole movie worth watching.
Acting was good
Direction was good
Story was very good
Dialogue was good
Effects were good
Bottom Line: Not a game-changer, but a very good twist on a frequently rehashed story.