My Canon 50 1.4 works fine, but doesn't get a lot of use, so I'm in no hurry.
But I would love to see a robust, sharp, contrasty, fast focussing 50 1.4 WITH IS.
Not holding my breath on that.
I think you're really missing the point of this lens. This isn't just some random 50mm lens that's maybe kind of good.
Read about the Zeiss Otus, and then imagine a lens that is 89% as good with autofocus. That's this lens.
The resolution data for the Sigma 50mm f/1.4 ART which has been verified by third parties indicates this lens is twice as good as anything other lens in it's segment with autofocus. In some cases this lens is five times better than competitors, that makes it good enough to make everything else obsolete.
For reference the difference between the worst superzoom available on crop, at it's worst setting and the Canon 24-70mm f/2.8L II on full frame at it's best setting is right around the same as the difference between this lens and it's best competitor.
This lens is a really big deal. Some people have been waiting for something like this for decades. It's the first standard focal length autofocusing prime with pro level resolution wide open.