Or "that other OS."
When I was visiting the DISQUS office a few weeks ago my coworkers and I made it a point to tease each other about our awful tool choices (especially editors). It's also come up among some other friends recently, so I think now is as good a time as any to try and explain why I use Emacs (and think you should, too).
A little history: I've been using Emacs now for about a year and a half. Before that I used TextMate for about 2 years, and before that it was Vim for about 2 years. I should note that when I say "used" I mean as my day-to-day, minute-to-minute editor. I still make use of all 3 pretty regularly.
The most important aspect of Emacs is that it can (often easily) do pretty much whatever you want (or need) it to do. Some people take this to extremes, with browsers and more inside of Emacs. I won't defend that here because I believe in the right tool for the job. What does matter is that you can often recreate any other editor feature within Emacs, and more often than not someone has already done it for you.
Where people often go "wrong" is that they assume customization should be done after you master the basics. That's the first step toward the anti-Emacs club. I think the tutorial should go into init.el and basic customization as soon as opening and saving are out of the way. If you use Emacs without customizing it, you're doin' it wrong. If you do something that pains you two days in a row, you're doin' it wrong.
Here's an example: Emacs teaches you commands like C-n and C-p to move between lines. If you don't like that you are free (no, encouraged!) to not use those and bind different keys (in this case the arrow keys are enabled by default). The same goes for saving, copying, pasting, closing a buffer, etc. If you really can't stand the key combinations then change them! I've set my Emacs up with a very OS X muscle-memory friendly configuration, Command-S,C,X,Z,F,G,W,Q all do what you'd expect. This isn't a sin against Emacs, this is Emacs.
Once you've given yourself a pretty basic TextMate like editor that you can at least use, you start the slow day-over-day growth of your own config (and thus your own editor). You can see my config for some examples. When you miss something from another editor, add it. When you see something new in another editor, you can probably find it and add it. When something (anything) annoys the hell out of you, change it.
Can you do all of this in Vim? Sure, kinda. I just couldn't get very far with Vimscript before banging my head against a desk. I feel like the Emacs "add-on" (they really aren't add-ons) community is larger, faster, and more engrained in the culture. Elisp is the editor.
I'd like to point out that I'm pretty bad with Elisp, you don't need to become an expert either. Elisp is also a pretty bad Lisp in my opinion, but it's hard to point out another popular editor written entirely with customizability in mind in a language that's usable.
If you're a programmer I think you'll enjoy being able to program your own tools. And what do you use more than your text editor? You're missing out.
Note: Since this was mostly about the ideology of Emacs I hope and plan to do a little screencast comparing my current setup to another editor (probably TextMate) to explain what I've done with my own setup and the crazy features Emacs has that nothing else seems to.