Can't get route directions from within big public transit infrastructures like airports, no multimodal connections with walking directions
If you try to route from the "Denver International Airport" (first search result for "Denver airport") to anywhere in Denver, GNOME Maps won't be able to propose any route, with any transportation type, because it doesn't get the relationship between the massive airport facility and its surrounding amenities:
This results in the Directions sidebar being unable to come up with a suggested route for anything between Denver and its airport, for example, even though in theory it could achieve that if it approximated the start location:
Edited by Jeff Fortin