I use vim because it works via command line. If I'm editing a file on my server, I don't have to open ftp, connect, navigate to the directory, download, edit, upload - I can just ssh in, navigate to the file, edit and save.
If you're good with regular expressions, the find/replace engine is spectacular.
Knowing your commands helps also. You can navigate through a file (or multiple files) with just a few short commands - without ever touching the mouse. In my mind, moving my hand to the mouse, moving the cursor, clicking, then moving back to the keyboard is way more work than switching between modes in vim (which is at most two keystrokes).
It's also got built in syntax highlighting for just about every language on the planet.
There used to be a bunch of assholes that posted on this part of zoklet here... But we systematically removed them like you would any kind of termite or roach.