I have little time to write about it as I like to write whole papers about films.
I know that I will not be saying anything knew while saying this but I feel like saying it.
Nightcrawler is smartly written, directed and played. 

Jake Gyllenhaal improved his acting skills so much that from now on he will be Lou Bloom for me like Javier Bardem is Anton Chigurh or Anthony Perkins is Norman Bates.

Rene Russo and Riz Ahmed are superbly convincing too. 

I have always enjoyed films with subtle or open social criticism. The Network, Gone Girl, Fight Club, Trainspotting, Taxi Driver, The Wolf of Wall Street, American Hustle, etc. A variety of films that have some sense of humour here and there to awaken the audiences, remind them of who they are, and how complicated life is in such a primitive world. 

It is not that we empathise with sociopaths, killers, gangsters of any ill-natured souls. We do not. We do not necessarily like them. Through them we see the society. We see what it does to us. We also see that some people need no reasons in order to be bad, and they should be treated, rehabilitated before turning them into trolls. 

We like to see cold-hearted but somehow interesting and intelligent characters because we do not usually know them closely in real life. We want them to be intelligent and interesting but not bad. We wait for the moment that they turn in themselves or become good. In most cases this does not happen but we still watch because they are unusual. We want to understand people like Lou Bloom knowing that we cannot.