Is emacs worth learning?

I think that it is definitely worth to spend time to Emacs. That is, if you have the time. The first 2 months you do not feel really in control, though every little bit you learn feels like a victory. Now, after 6 months, I am amazed with the possibilities and wrote so many little tweaks. Before, I never did any programming and now I wrote a small little package for Emacs. Life is great.

EDIT in 2019: I do not recommdend it anymore. There's a steep learning curve, and with the great editors available these days it is not going to be worth your time investment. Especially since the amount of people who will be able to add new functionalities to Emacs will decrease (Emacs-Lisp is a shitty language)

Emacs is highly worth learning. While I don't like slideshare, let me link you to what Matz had to say about this topic.