Briefly what negatives come with this - I assume some positives??
Negatives are lack of tactile feedback, no hard stop at infinity or the MFD (for macro and astro, its common to just set to one end of the focal range), and that the lens needs to be mounted to a powered-on body to change the focus. The last one really only matters with lenses where the front element extends with focusing (like the 85L), where you have to remember to retract the front element before unmounting the lens. I don’t know of the RF 50/1.2L has an extending front element, but the focusing group comprises the front 2/3 of the elements (the front 11 of 15 elements).
Positives are that you can change the direction of focus (presumably via a camera setting), not sure why you’d want to.
Mixed is the focus throw can be variable (it is on STM lenses, I presume it will be/can be for RF lenses). I’ll just copy this bit from my review of the M18-150: With a fast manual rotation speed, the focus ring must be rotated 150° to rack the lens through the full focusing range, while a slow rotation speed requires a rotation of 240° to cover the same range. The idea behind this is to allow faster manual focusing with a shorter focus throw when moving between close and distant subjects, while also allowing precise fine-tuning of manual focus with a longer focus throw. I call it mixed because while it sounds nice in theory, in practice some find it annoying and difficult to get used to.