Understanding the film making style

So i saw this movie two days ago and i have to say that i liked the scripting and acting(at times) alot. Both the above things made me feel that the director is a wise guy when it comes to selecting subject matter and getting the expression out of his actors.

So what i don't understand is why did he choose this particular style of filming: i mean with static camera and not showing the faces or expressions of his actors?

Is there a link or video where i can understand the reason behind it?

Thanks for any help in advance.