Can you enlighten me of some of it's virtues? Seems like a steep learning curve, does it pay off?
The key thing about Emacs is that it's completely customisable and extensible. While all decent editors share some or most of its features, Emacs is open-ended so that if a feature you want is missing, you can add it using Lisp. Chances are, someone has already done this and the source is available somewhere - just drop it into your .emacs configuration file and you're away.
Because of this, it has good-to-excellent editing modes available for almost any programming language you can think of, plus for many common *nix configuration files etc. The support for each language ranges from simple syntax highlighting in some, to full code completion / compiler integration in others. Also available is Lisp code to do things like hooking into online dictionaries or translators etc, full usenet / email apps... whatever someone has taken the trouble to write.
Because Emacs has been around in one form or another for so long, it's developed its own, often idiosyncratic way of doing things - this does lead to a steep learning curve, but when and if it 'clicks' it really can improve productivity. It's really not that difficult to get to grips with as a normal editor, the more esoteric aspects can be picked up as and when you need them.
Emacs shares the same philosophy as *nix in general and the open source variants in particular - it provides a vast range of small tools and the environment in which they can be glued together to suit your working style, and if you don't like the way it does something, change it...
I think I heard someone say "It doesn't make your coffee, but if you tweak it enough..."
The people I know who use it won't go back to anything else. Yes, they say, the learning curve is steep, but there is so much you can do with emacs, it is worth it.
> "It doesn't make your coffee, but if you tweak it enough..."
Hehe, the most common icon for it is an overflowing kitchen sink ;)