I ripped the bandaid off last month, there's definitely fiddling and hdr is still in early days (works in gamescope, but found that can have issues with my nvidia card), I've been playing veilguard on proton ge for the last week, and proton experimental supports dlss frame gen now which is huge for me.
It's definitely in the good enough state imo, and it seems to rapidly be getting better.
No problem, most games I've tried run without much fuss just with proton enabled. For others, protondb is great (pointed in the right direction to get Jade Empire running) or fiddling with settings yourself, gamescope helps a lot even if I've found it has some issues with nvidia cards (had games freeze with hdr for example), more of my issues are probably related to having an ultrawide tbh.