Sorry, why people hate this lens? There are not enough pictures make it deserve BAD reputation yet. Why so negative here?
This focal length is not my priority but does it make it a bad lens? The op's pic is in cloudy day without any extra effort in editing to bring out the contrast and color, he want to show the sharpness of the lens, which I think it did showing it is good. Which corner we are talking about?
F5.6 with 25mm may not enough to keep everything sharp, especially with 12M picture, I think the photo will be benefit more with f8 or so before diffraction kick in.
Plus, I never think modern day Zeiss has any obvious advantage in sharpness compare new Nikon and Canon offer. Say a 35mmf1.4, comparing Canikon offerm it is not sharper. But people still love it. Why this lens get treated totally different??