Pretty great actually. Not as out of the box as on Windows but almost there. Firstly you get a vastly different experience depending on if you are using Steam. Since I have my entire library on Steam I can’t say anything about other stores. There’s imo 3 points where the experience still differs:

1 - you have to enable Proton as the default compatability tool, Valve has a guide for it and the setting is pretty straightforward to find.

2 - Most games just work now but a few don’t in those cases things like protondb.com are an enormous help.

3 - Mods are hit and miss (Steam Workshop works fine) depending on the game, for Cyberpunk for example I had to mess with the Proton Config a bit but there were guides for it. However since we are now in a niche of a niche (modding a game running proton) you’re likely to run into unexplored territory