Scorcese doesn't use a lot of close-ups on DeNiro, except during the fight scenes. It seems to help maintain the distance from the character. We're watching this character from a certain remove.
When DeNiro gets angry or is fighting, Scorcese goes to slow-mo, to show the speed of adrenaline through its opposite (because adrenaline slows time). You think that adrenaline and pain speed things up but it just speeds you up, so that you're moving faster than the world around you.