I have the firsthand experience, and the fights are as you'd expect; very lightly loaded, more available rows than passengers on a 320, masks and temp checks required before boarding. There are lots of negatives which are actually positives, assuming you are not a needy/entitled passenger: no terminal noise, no gate lice, no zone boarding, no jetway queues, no jostling, no shortage of bin space, no shared arm rests, no lav lineups, no perceivable stress, no attitude and no need to purchase any fare beyond basic economy.