My experience with it is kinda awful.
In my 2.93 renderman crashes a lot, but I wanted to use it for videos not for still. I recommend it for still images
Just one personal obvious tip, as for Cycle and Eevee, start Shading in Renderman. With Imported or appended characters or props, it usually gives you bad results.
If Renderman doesn’t want to help you and the rendering keeps crushing, I suggest the F12 button. Usually the viewport view renders just fine.
Let us know how it goes
Also the Renderings, when it works, are majestic. Especially with hair particles and eyes, in my opinion.