Most generated maps are cities on nearly flat ground, where the elevation data hardly matters. Here it is the whole map. Standing on the railing at Mather Point you look down a stepped slope of cliffs, a wide bench and then a slot with the river in it, and every one of those shapes comes from the real terrain. The Tonto Platform, the broad bench that the Bright Angel Trail crosses to Plateau Point, is easy to pick out, and so are the buttes above it, like O’Neill Butte on the ridge north of Yaki Point.
The developed rim makes a good contrast. Grand Canyon Village is a small town: a loop of roads, parking lots, lodges, a rail line ending at the depot, and the Rim Trail running along the edge, all from OpenStreetMap. A world that is all canyon would be hard to orient in. Here the village gives you a base with roads, and the trails take you down from it.
Here is what the map does not do. The real canyon walls are bands of color: the cream Kaibab Limestone at the rim, the pale Coconino Sandstone cliff, the red Hermit and Supai layers, the red-stained Redwall cliff and the green-grey Bright Angel Shale slopes. The generator picks surface blocks by slope and land cover, so steep walls come out as grey stone, cobblestone and deepslate rather than red and buff stripes, and the illustrations on this page are brighter than the world.
The heights are compressed, so the walls are about a quarter as tall as they would be at true scale. There are no building interiors, and Hopi House, El Tovar and Phantom Ranch are plain shapes. What you get is the real layout of the rim and the real shape of the canyon under it, down to individual side canyons and buttes.