WMR compatability is fine. You have to start the Mixed Reality Portal (the vr software) before starting a game or there’s a pretty good chance the game won’t render to the headset, which causes bad language every now and then when you forget, but it’s nothing major. Generally speaking, if I start MRP, then SteamVR, then the game I don’t have issues.
The portal has some annoying QoL features, but nothing that breaks games. The biggest issue I have with it is that it will randomly start itself while doing other stuff, so it’s probably better to not leave the headset plugged in all the time (probably a good idea regardless, unless you spend a lot of time in vr).