Lack of good storyline.

Simple and well acted, it has tension enough to knot the stomach.

When a movie has you begging for it to end not even half way through it's pure crap. We've all seen this movie and this characters millions of times, nothing new in it. Don't waste your time.

Just intense enough to provide a much-needed diversion, just lightweight enough to make you forget about it soon after it’s over. It’s not exactly “good,” per se, but it does what it sets out to do in terms of putting us on edge, which makes it … successful?