My take on what would make someone want to give fork a try is this:

A lot of CMS's try to integrate both a CMS and a blog feature and don't do such a good job. Yes, WordPress is by far the best blogging tool available, but if you want more you really have to work over some of the modules to make them do what you want. With Fork CMS it comes closer to that melding of CMS and Blog than some of the other's I've tried -- and it does so without requiring the heavy-handed administration the likes you'll find in Joomla and Xoops.

Don't get me wrong, I really like Drupal, Xoops, and Joomla...but Fork CMS offers a nice middle ground that no one else seems to be offering.