The only purpose of chromatic aberration in any game is to be disabled in the options menus lol
Seriously though, here's an exaggerated look at what Chromatic Aberration does
It's usually not this extreme, but you get the point. IMO it always looks bad and I don't get why devs love it.
Film Grain is
This sort of noise added to the image to simulate the look of stuff shot on film.
Vignette ususally darkens the edges of the image to a certain extent
It's pretty light in this game though.
Motion blur basically adds blur to the image when the camera moves. It can help reduce judder and make the motion look smoother, specially in low framerate content (like 30fps quality modes). Though I mostly disable in games running at or above 60fps.