I've beaten it. It's really hard. Prepare for some real challenge. It is way harder than the base game and a true test of skill.
The difficulty doesn't really concern me. I got all of the achievements on Doom and Doom 2 on console. Up to and including punching out a cyberdemon, I got it.
I want to know if it's good. Thinking about holding out until part 2 comes out as well as the Series X enhancement patch.