Indeed it is very wavy but you can sort it with a single click in ACR or LR. You just need to download a profile.
Sharpness should stay very reasonable all the way unless focus is off. (you can't trust factory calibration on these, but it only takes lifting some rubber and selotape for a fix).
The corners have some nasty colour cast. It can be masked in post with a few simple steps, or even cropped out. It will never be a problem for astro. I think even vignette could be left alone, as you just don't want ultra noisy corners if you fix it.