Org-mode, as a mode, is obviously awesome. The ability to move around whole blocks of text, for re-organizing documents and the usability of tables are just two brilliant features.
But, the org markup itself is such a cool thing. I've been
rst all day, and it's such a pain to find out where
your headings are, what level your current sub-heading is at, etc.
(I'll probably do a bit better, with some getting used to. I'm an
org-addict. ;)). With org-mode it's so intuitive! It's so easy
to find out, with just one quick look! I don't think any other
markup has this coolness! Org-mode FTW!