emacs per se is not that interesting. It is what you can do with emacs that matters.
emacs user generally feel like they created a tool that is so adjusted to their uses and habits that they barely notice emacs at all. They tend to speak about a symbiosis with the tool.
To my mind, not only do I agree with this, but also I think it provide most on the features of a good ihm, providing satisfying default behavior, while allowing the user to customize every part of it to make it fit the user.