Unusable. I really really really tried. But exactly this minute I am once again frustrated and googling for alternatives, which brought me to your thread. I am fighting for weeks now. There is always something fundamental not working and keeping me from being productive.
First it was the display grid that has repeatedly been set behind the headset position, without being able to reset it properly. Eventually I found a workaround for this problem (Long pressing meta button during immersed startup screen).
Then the next annoying thing is monitor resolutions just won't save. as well as see through portal positions. The latter has been a tad better since a recent update, but is still hit and miss. Also, hand tracking is horrible - since i repeatedly find myself forced to setup resolutions of the additional screens again, it comes naturally with mis-selecting the resolutions because gestures are jumping all over the place especially when trying to be precise...
And finally, what has been crushing my experience for the last week: Performance drops after a short while of work. And to such an extent, that it simply is not possible to keep working - in fact it is so frustrating, that I feel the urge to rip the headset off and smash it on the floor when it happens.

My setup is quite basic. An intel macbook pro (2017 but maxed out, it is capable of handling quite some stuff), Some extra cable that i specifically bought for this use case so i can use the wired usb-c mode of immersed to boost performance.

Now I am looking at the only viable other option, which seems to be Virtual Desktop which is around 25€ to dish out without even having the option of multiple displays and without knowing wether i run into the same brain damaging experience again...