Here’s the 9to5Mac review for the DualUp. Stressing its utility for productivity when using MacBooks like the Air which can only have one external display. Why not make that display a doubled display, then?
Disappointment: he didn’t try Stage Manager, or at least he doesn’t mention it. I watched the whole video out of curiosity about that. 
My husband (UX design) got one of these and really likes it. He uses it sideways, not that it matters much with this thing. He’s reworking his set up, so this thing took over the center spot from a traditional 16:9 27" monitor. He tried then turning that one portrait and having it off to the side, but it was just too tall.
There’s currently some experimentation going on for what the second monitor will be now, but between the 16" mbp and the dual up, he’s very happy.