I'm using Scrivener to write Smartphones for All - Using iPhone and Android to build independence for atypical minds.
It’s brilliant software. On my Mac it uses the same text editing engine as TextEdit, including the same RTF format. So, like the Nisus Writer I once used, my writing is indexable by Spotlight and almost as future-proof as plaintext. (I thought RTF was dead. Guess not.)
Apple’s text engine has its share of bugs and limitations, but for basic text work it’s good enough. The primary weakness is table layout, but so far I’ve worked around that. Scrivener manages the tasks TextEdit can’t do, like page references, footnotes, internal links, document structure and the like.
The real brilliance though is how Scrivener merges concepts of software code management with the traditional word processor. It treats text blocks as though they were blocks of code, including simple version management and “compiling” to multiple output formats (PDF, EPUB, etc). Rather than use some horrid database store, Scrivener leverages native Mac file structures to manage its data. Extra brilliance points for that.
On this compile framework Scrivener layers a rich set of power user features. The latter, I admit, can be overwhelming. I recommend learning the basics from the initial tutorial, then start writing and learn additional features over time.
All software dies. One day Scrivener will die too. But with the ability to complete to multiple formats, and the use of native file system semantics and RTF data, Scrivener is as future proof as any power tool can be .
 Scrivener’s design is a guide to how photo management software should be built. Please, someone do this.