The Canon RF 50mm f/1.2L USM lens is pretty remarkable, especially when it comes to sharpness at f/1.2. From what we've found, it's not easy for lenses to maintain sharpness at such a wide aperture, but this one manages quite well.
At f/1.2, you'll generally see excellent sharpness in the center of the frame. The corners might be a little softer, but that's a common trade-off with wide-aperture lenses. Usually, stopping down a bit can help improve corner sharpness if that's a concern.
Also, the shallow depth of field at f/1.2 is pretty amazing—it gives you that dreamy bokeh that really makes portraits and artistic shots pop. It kind of makes the sharp areas stand out even more by beautifully blurring the background.
One thing to keep in mind is that this lens doesn't come with optical image stabilization. The manufacturer suggests pairing it with camera bodies like the EOS R5 or R6 that have built-in stabilization for better results.
This combo can give you a decent level of stabilization, though maybe not as much as you'd expect—perhaps around 5 stops instead of 8.
If stabilization is a priority for your photography, especially in low light or for video, using a body with stabilization or considering a lens with built-in IS could be worth it.
But for many photographers, the sharpness and image quality of the RF 50mm f/1.2L, especially for portraits and general shots, can be a huge draw.
Ultimately, using it to its strengths—like its sharpness at wide apertures—can give you some fantastic results. Just consider your needs for stabilization and shooting style to get the most out of this lens.