What is so great about Emacs?
Emacs is Extensible
The GNU Emacs manual describes Emacs as the extensible, customizable, self-documenting, real-time display editor. And with a good reason - it's extremely easy to add new features to Emacs, due to its integrated Emacs Lisp interpreter.
Why do I need Emacs?
Emacs helps you be productive by providing an integrated environment for many different kinds of tasks: All of the basic editing commands (and there are lots of them) are available no matter what you're trying to do: write code, read a manual, use a shell, or compose an email.