One of my monitors is 9:16 - I've rotated it 90°. It's terrific for reading PDF documents, web pages, a terminal, and the IDE.
The only thing it's not really good for is the email client, video, and pictures. For those I have another monitor in the standard landscape configuration.
I used to have a similar setup, but I replaced the dual head setup (24" 9:16 and 30" 16:9) with one ultrawide one.
I suppose just as wide 16:9 display would have been even nicer, but it's fine. There are some benefits in window placement in having just a single screen, even if window managers could work better for this use (e.g. have a "second screen" region where there are separate workspaces).
