It's plenty usable. Most of the problems with the claude TUI stem from it being a TUI (no way to query the terminal emulator's displayed character grid), so you have to maintain your own state and try to keep them in sync, which more than a few TUIs will fail at at least sometimes, hence the popularity of conventions like Ctrl+L to redraw.
I don't know what a TUI is (i'm guessing "terminal ui" as if the term CLI doesn't exist lmao) but yea, they could have put effort into their product and not forced people to use their atrocious ncurses interface which is like the worst of all worlds: text interface without the benefit of the shell, zero accessibility.