Is it still a partial port or does it take a different approach?
It looks like you've forgotten to install one of the modules that implement panels.
From: drupal.org/project/panels

Panels in Drupal 8
We’re actively working on Panels for Drupal 8 which works with the new layout_plugin module and mainly is an interface to configure and store these layouts.
Panels is an API in Drupal 8
In order to use panels, you must use an implementing module. Currently, Page Manager and Panelizer implement panels.
If you’re interested in following the Drupal 8 port in detail, follow #2169319: [meta] Drupal 8 port of Panels in the issue queue OR join us on IRC every Tuesday at 12 noon CDT (UCT-0500) in the #drupal-scotch channel for our weekly meetings.