Image Viewer (Eye of Gnome) is set as default for launching photos in settings. This is problematic as we should probably be emphasizing Gnome Photos. Image viewer lacks even basic editing features and the UI/UX seems better under Gnome Photos.

Additionally, in a new Gnome Boxes install of the 2018-05-30 ISO, Gnome Photos is not listed as an option in the drop down box of the default applications section.