Features

of StatiCMS:

Dependency checking
only content that needs to be updated will be updated. Thus, if you make a low-impact change to a large site, the update will be quick. As a user, you do not have to define the dependencies, this is done automatically.
Plugins
thanks to plugins you can generate any content you like from any input you like. The catch is that you have to do some programming for this. See the plugins page for an overview of available plugins.
Simple but powerful configuration
The basic configuration file is very simple, however, since the configuration file is a Python script, the full expressive power of the Python language and run-time system is accessible from the configuration file. This allows very powerful configuration settings, yet keeps things simple.

of static websites:

Secure
because the site will have static content only, you do not have to worry about people breaking in to your website via dynamic scripts, unless you explicitly put them on your site. With static content, the only thing you have to secure is the webserver itself.
Fast
static content requires a lot less resources from the webserver and is therefore faster.
Economic/Green
because less resources are required, you can save money and energy.
Easy to mirror
static websites can be mirrored more easily.