The 'violence' is implied except when Meyer's character saves the damsel in distress. You see dead bodies, but what, who, or how the acts occurred are just as vague and non-complete as the rest of the movie. I stuck with it because I purchased the movie based on the actors and the preview of a good watch. It still took two viewings to finish it.
Kaufman is particularly good at shooting shadows, silhouettes, and angles to keep the audience on their toes. The sound design keeps Invasion of the Body Snatchers mostly quiet or silent so that all the sounds echo and reverberate deeply. You hear every gross gurgle, human scream, and alien shriek in the movie loudly.