The manually inserted vignette seems to be all the rage these days.
I find it a little ironic how much research and development and money consumers pay to avoid the vignette in camera only to put it back in post production. For or against? As always: it depends.
Many images, especially those with a lot of peripheral detail, do well with a vignette. It helps focus the viewers attention and damp down extraneous information.
For me, it is more of a comment of the skill of working withing the limits of the camera. The more advanced our cameras get, the more information they capture and the more flexibility we have. the camera still has limits like dynamic range and pixel count. Know these, however, puts a photographer in a great position to work around them or, this is the great bit, exploit them.
the image below was shot on a point and shoot just for fun. The auto-focus makes it difficult to create interesting composure so the main subject of the rocks was slightly out of the focal plane. Also the poorer optics and smaller file gave a grainy look to the image.
I know this and so in post production I used this grainy feel and emphasized it to give a grungy kind of ruptured feel that I enjoy even though the limitations initially pissed me off!
Beginning with the end in mind is important and knowing the extend of you equipment, including post production, will make images or break them.
Thanks and be good, Jeff.