The best part is using your existing development workflow to maintain and deploy your documentation. The whole idea is that you can manage your documentation just like you maintain the code. Their build and hosting make is simple to just add docs and get them online. And since the docs are versioned you can provide relevant documentation for each version of your software. The doc versions work with repo tags (or branches, commits, etc). The project template gets you started super fast and your online docs look good. Review collected by and hosted on G2.com.

They use Sphinx to generate the docs under the hood, which uses reStructuredText markup language. Sphinx extends the reST system with some of it's own stuff. That's pretty good. But I prefer the simpler syntax of markdown. This is probably a pro rather than a con for most since reST is more feature rich. Review collected by and hosted on G2.com.