I have to take issue with it being sharp wide open. It's not remotely as sharp at f/1.2, as for example the 135L is at its wide open f/2 (not even in the center...and at the borders the 85L is pretty soft, and suffers from coma). Also, the 85L has a fairly high vignette anywhere near wide open aperture.
My copy of the 85II L is really sharp wide open. It's sharper than my 135L wide open. My 2nd photographer's copy isn't quite as sharp as mine but it's still very sharp.
I'm really not that fussed about coma, it's very easily correctable. The point of the 85IIL is that it's a portraiture lens, hence the soft corners, dreamy bokeh and strong vignette wide open...it's an optical photoshop look...and really works wonders with portraits.
No doubt there's sample variation, I suspect you have a soft 135 and the 85 I rented was slightly soft. I fully realize it's a portrait lens. But as for coma being "easily correctable", I'm not sure how you do that.
@CarlTN +1 on your coma comment.
@GMCPhotographics Vey interesting on coma correction! Maybe you know something we don't