If you want to
edit something and you like ed, ex is a perfectly adequate substitute.
That's rather subjective.
The `ex` command set is very close to `ed`, but subtly different in
(possibly?) annoying ways.
I believe it, but if you've just booted up a linux box and you need to
edit some config file, ex is close enough to ed to get the job done. It's
a lot easier than trying to install emacs.
Once things have settled down, sure, use whatever editor you want.
R's,
John