The fastest way to “demo” it is just by pointing to the manual:
Pretty much the main problems are well documented. What is not documented is more or less a logical follow through of the documentation. So, not a critique on the manual, more a demo of its concerns.
To your scene: Well that is a still that you shared above. Not your typical work either, right? If the background would move away, just a simple plane. The shadow would be the absolute the same, if you place the camera at the light source. No change, absolute un-natural.
However the main artifacts will show if the object light distance or relation changes. As it is just based on raster points that will create a texture, then, it might be for a while between certain points and then between others for a while.
A more typical set up would be rotation, where the light is static and the object moves. The Soft-Shadow has a lot of trouble to keep things without blotchy flickering., or lets call it Lava lamp aesthetic.
Anyway, tight gaps between objects, the missing qualities of natural shadows and the inability to cope with motion set this option apart from any other light source in Cinema 4D. The biggest advance is given when nothing moves, and no small gaps are presents or the whole duration, then a single calculation can be used for an endless amount of images. I think there are better options then, baking the shadow for example.
I have put three rough examples based on my three points in this link:
I find it, besides its shortcoming, that the aesthetic it often provides has that ‘90ish-CGish aesthetic. But that is just a question of taste perhaps. If you’re happy and nothing bites your project, use it. I always think that after a while no one really cares how long it took to render, but your are stuck with the results perhaps endlessly.
In the scene you had shared in a different thread, the main body is 100% reflective, hence it doesn’t take any soft shadows, and Hair (default) has no concept of soft shadows at all, it is a volume effect that doesn’t care about this. My concerns were more:if you switch to polygon hair.
Anyway, one of the most natural qualities, is the fact that with distance it gets more blurry. Perhaps set the parameters hight for the soft shadow. Check the area shadow as comparison
My best wishes