Noldo

To be honest, I believe that the coating is the same. It just is not explicitly written. It is cheaper to use totally the same glass then to develop new and worse lens coating. Looking forward to this lens.

Your lens is definitely decentered or slightly off. I have one very similar and i see images like this in one corner when shoot at 18mm f2,8. 21mm f3,2 or what is the widest aperture is okey. Also 18mm f8 seems to be okay on my lens. Image is also okey when i focus on the soft edge. Then the whole image is sharp. You should try that. OIS off, 1/250 ss and various focal length wide open and try to focus on the corner of the image. In my opinion you have a bad copy. There is a lot of bad copies of 18-55 out there.