I haven't yet had a personal experience with this lens.
I am considering to get it, knowing that its IQ is limited.
I am not using f/1.x that often to justify the prices of the much better L lenses.
It was clear to me from the start that its sharpness wide open would be only good in the center to mid frame.
It was clear to me that the bokeh wide open exhibits “cat's eye” corners.
I thought, Canon could do a bit more about aberrations.
I am sure, I'll have to take a personal look at it.
Just to make it clear for me:
Your opinion is based on hands on experience or theoretical thoughts form MTF and the reviews in the web?
Thanks in advance for your clarification