I have one and I can confirm it is a very good lens that delivers. I like the image quality out of it and it is not at all unwieldy in my hands (but then I am comfortable with the 85 1.2).
It's a very specialized lens and less versatile (in my opinion) than an 85. My only issue with it is that it is not magic to my eyes like the 85 1.2 is

YMMV
The Canon RF 135mm f/1.8L IS USM looks like an incredible lens, especially for portrait and event shooters who want sharpness with stunning background separation. I appreciate how reviews highlight its balance between speed and image stabilization. It reminds me of how preparation tools like a
pa notary practice test give users confidence, just as this lens gives photographers confidence in their results.