Many people consider the Emacs *scratch* buffer mysterious. This is true even though, by default, it includes a message telling you what to use it for. I like it and use it often. Others, not so much.
Despite that default message, I never use the *scratch* buffer for notes (I use Org capture for that sort of thing) but I use it all the time for trying out a bit of Elisp or writing a function for my init.el file. It is true, though, that the majority of Emacs users don’t write in Emacs Lisp and really have no use for the *scratch* buffer.
Most of us know that you can eliminate or change the message in the *scratch* buffer but that doesn’t address any real problems. It is Emacs, though, so of course you can configure more than just the message. Bozhidar Batsov over at Emacs Redux has a nice post that shows you how to configure the default mode of the *scratch* buffer. Thus, to use Batsov’s example, if you’re a Ruby programmer you can configure the *scratch* buffer to use ruby-mode as it’s default mode.
I’m happy with having the *scratch* buffer come up in Emacs Lisp mode but Batsov’s post may help make it more useful to others who aren’t Elisp programmers.