The sharpness (definition accutance + + contrast) seems a little better on my D800 but the former was already very good.
At f / 2 is already very touched to quite a magenta center fringes in the corners.
At f / 2.2 the sharpness is almost maximum in the center, the corners are less beautiful, but the portrait is the perfect opening.
At f / 2.5 center is optimum and progress more by closing the diaph: With this lens you will close the diaph for the CDP or to advance the corners.
At f / 2.8 the corners are very good.
The af is faster than the old version and a hit every time.
The bokeh is more beautiful than the old version.
Legere distortion but the camera raw automatically corrects for me.
Vignette ugly enough to f / 2.5 - invisble from f / 2.8 unless you look carefully. Corrects with camera raw.
Finally, for the price, this should be in the bag for all serious photographers.
even if you use it little, it will last for years and will probably live up to the coming generations to 40-50Mp sensor as its optical performance is good.
