Distortion is crazy but there is LR preset you can download from Adobe.
Sharpness is good, but it can go pretty bad over time for no reason.
In my view 16-35mm latest zooms negate the need for one.
As Daguirdas says, distortions are odd! There are alternatives if you're happy going 2nd hand and waiting for them to crop up - I was lucky and found a Tamron 14 f/2.8 when I was after a fast ultra wide. AF and auto aperture (Nikon Samyangs are AA but MF.) 2mm at the wide end might make an appreciable difference.