It's interesting that to me, this looks more "3D" than normal street view. I would guess it's the thing about the human brain filling in the detail...
Pick a location and compare it to the standard street view on google maps, and you'll notice a similar "more 3D" appearance.
The reason is that it's using three.js to map the panorama onto a spherical geometry. This is actually quite an old trick used to give a more immersive feel to panorama viewers dating at least back to the days of QTVR.