I bought this lens a few weeks now, and after using the Nikon 85mm f/1.4D AF Nikkor Lens for Nikon, and The Nikon 85mm f/1.4G. I really wanted to say that this lens is awesome. The Sharpness is comparable or Better than the 85D, and controls flare much better. The Focus is faster than the "G" but a bit softer wide open.
The key benefits of using the "G" is WEATHER-SEALING, Nano Crystal coating (To prevent flare), and brand Loyalty. The Sigma in my regards is an excellent replacement