[Klaus]

The dark edges are not so much gone because of the distortion correction, but more because of vignet correction (realizing that after reading the review). Thats still bad... At least at higher ISO settings.

 

It's really the distortion correction that makes the difference here. The barrel distorted corners are stretched out. With pincushion distortions you tend to keep the corners but stretch out the middle part (alternatively you shrink the edges and scale up the whole image.