Bob Mitro, Owner of Publii:
Unlike static-site generators that are often unwieldy and difficult to use, Publii provides an easy-to-understand UI much like server-based CMSs such as WordPress or Joomla!, where users can create posts and other site content, and style their site using a variety of built-in themes and options.
I love static-site generators, my favorite being Jekyll. The performance and security benefits are pretty amazing. Still, I have to agree with Bob here, they're not always easy to use for non-developers. Publii looks like a nice option for clients or those of us who prefer a nice UI.