Beware Proton 4.2 with this game because it had an issue where the keyboard keys would not respond following a cut-scene of which this game has more than a few. But 3.16 Proton and now 4.11 don't have the issue. There was also a visual bug that showed up in a very few places that was annoying but would subside (weird gray rays that would shoot all over across the image) but even this small issue is mostly gone by using PROTON_USE_D9VK=1 option.
Runs fine, however mouse is not visible in Steam overlay, though you can still select things. Antialiasing is greyed out however you can select anisotropic filtering levels from the Advanced tab. This is a game that requires PhysX but it installed and ran fine. Sound and speech work great. All other options seem to work too. So, it's just little things that have minimal effect on gameplay.
No noticeable issues