Imaging Resource has their full Panasonic-Leica 12mm f1.4 review up. The field map basically says it all, but as you can see, the lens is sharp in the center and across most of the frame from wide open, and is essentially perfect across the frame by f2.8 and f4. I believe Imaging Resource reports post-correction values for all their testing, but this lens also shows essentially zero distortion on that basis. I'm fine with software-corrected values, as long as they also present those post-corrected values for the sharpness testing. The proof of the pudding is in the eating, as they say... I guess it's what you'd expect for a $1300 M4/3 lens, but like the Nocticron, the performance is beyond reproach. I can't afford it, but it's very impressive nevertheless!