I fell for the hype that Textual always gets on HN and actually used it for a mid-sized commercial app a few months ago. I figured it was a 'safe' choice, given all the developers here who seem to like it, and it was the only TUI library I could find with corporate backing. Here are my notes.
1. Considering it has actual paid developers working on it for quite a while and VC funding, it still lacks a great many features that I took for granted in all the non-commercial TUI libraries, e.g. menus and dialog boxes.
2. The async nature of the library is unpleasant. Can never be sure when/where your code will run.
3. Lots of 'magic' Python variables and methods that you have to override, but there's no way to discover them in your IDE through the type system.
4. Using CSS for laying out a TUI app makes no sense (unless you are a web developer and have Stockholm syndrome from using it for web apps?)
5. It seems to leak memory.
Eventually re-wrote the app from scratch using a different library that gets far less hype and spends no time marketing itself. The result was much better in every way.
Like, hell, their examples have some *HUGE* buttons, starting with a calculator app that is all buttons - who is going to click on those? The calculator-with-buttons barely makes sense for desktop GUI apps (it was helpful back in the 80s when everyone had a physical calculator on their desk to help see the metaphor of the "virtual desktop" and it is arguably helpful on touch screen devices today for obvious reasons, but on a machine with a keyboard it is superfluous), let alone TUIs.
If you want to see a TUI that actually looks good (though a bit too much on the fancy side, but it doesn't pretend to be something it isn't) check btop: