This movie was both fun and terrifying. Jake Gyllenhaal's performance as Lou Bloom will certainly frighten you. He is brilliant when paired with the amazing monologue style rants written for him.
Lou Bloom is a driven man reminiscent of a sociopath who finds he has a talent as "nightcrawling" in that he takes videos of true crimes as they are happening to be broadcast on the news. His motivation and seeming lack of empathy allow him to break through and take the controversial images, and sell them with a strong aptitude for negotiation.
As a character, he grows more and more "motivated" and seems to learn his business in such a way to bring him amazing success, but to the determinant, perhaps, of his assistant and the victims of these crimes.
The writer/ director of this movie (making his directorial debut) certainly understands fear and comedy. The simplest scene was made into a laugh by the angles and cuts.
It's funny, and enjoyable, but still terrifying enough to feel like a real horror thriller.