It is a reasonably good lens with pleasing out of focus rendering, good to excellent closeup and portrait performance. Best results come at slightly narrower apertures where for example product shots are perfectly detailed even on 50mp sensor, which is a great result.
I find infinity performance slightly compromised particularly on ultra high Res sensors. Definitely usable but no match for any sigma art.
I bought 70mm art recently. I find them interchangeable. Sigma has a hair better resolution and is considerably wider favouring some product shots, while canon is longer and come with much better autofocus, and image stabilisation for handheld work.
I don't have plans to upgrade to RF, but if I was buying today this would need to be carefully evaluated also taking into account the cost. I read reports from pretty reputable sources online that there is notable focus breathing issues making it only usable at f2.8 or f8. You will have test to be sure