I need to disclaim that I am not affiliated with the project, and have actually been pretty critical of it in the past. But I tend to agree with the author's reasoning across most of the blog, so I believe there is real merit to the shell.
Who knows, maybe in a few years we'll all be writing YSH!
I haven't switched to ysh. I personally use Zsh for my interactive shell, but I write my scripts in a variety of shells.
You can start with Ysh in its Bash-compatible mode, individually enable new features with shopt. Those features include:
Not splitting or globbing $foo by default (this is shared by Zsh and Fish)
A Python-inpsired parsing mode, which should supersede arithmetic mode (induced by ( ) in tests, $[ ] for string splicing and @[ ] for array splicing)
Strucutred data
New functions which return structured data (Oil calls classic shell functions "procs", because they behave a lot like external programs with extra side effects)