DrupalX sits on top of Drupal just like Drupal sits on top of Symfony and Symfony relies on PHP etc. We're putting another "layer" on top of the cake. That's all. So: Don't complain to the Drupal developers if you got a problem with this framework. You have been warned ;-)
DrupalX comes as a single module. It tries to be a one-stop solution, providing an easier API, fixing/evening-out common bugs/problems, extending the Twig template language and much more. It tries to solve all common problems in one go - just to do one single thing: Let you create flexible websites fast.
Everything is done without any patching. Installing the module is already sufficent to make use of all the new features that DrupalX provides. Especially for some of DrupalX's quite fundamental extensions to the Twig language, this sometimes means reaching deeply into the bag of tricks to make it all possible. The big advantage, of course, is that you won't have to worry that much everytime you're upgrading your Drupal installation.