I am using same feature and in fact graphic level suffers an improvement.
I only activated it cause im using Gaming option in global graphics that automatically runs with anti lag and image sharpening.
My question is : this only makes sense if u use low level graphics or in medium or high makes sense too?
It's not necessarily just for low graphics profiles, but rather to make the image more crisp, irregardless of graphics profile. Some games might look "foggy/blurry" even at highest settings and sharpening can help in bringing texture detail out more.
Furthermore, it helps for making older games' resolutions (1024x768) look more native, which do not support modern resolutions (such as 1080p) by default; for example, modern flat panel screens can only display one native resolution; all other resolutions has to be upscaled/downsampled (pixel duplication/pixel averaging) which results in a muddy image; whereas CRT monitors used to be able to display more than one resolution in their exact respective amount of pixels (640x480, 800x600, 1024x768, 1280x1024) which resulted in quite a bit clearer image.
And since a lot of those older games used DirectX 9 already, it's quite necessary.