Group

One big missing part of the Group module is setting up friendly URLs that contain the group in the path for group content. You can't set this up in Pathauto -- the tokens are too limited to handle this correctly.

The corners of Drupal 8 that aren't there are quickly dwindling, but there are still some that need to get worked out. While upgrading our internal issue tracker, we hit a new one -- getting a group context set via a URL alias, and generally keeping posts within a group.