I looked at the online demo, it doesn't appear to be 3D model.
But if it is based on 360 photos, how does it perform the transition between different viewing locations?
Streetmap, for example, can't do very smooth transition.
You can see the models through google maps on the normal web interface. If you go to a city, zoom in so your screen is a few blocks across and select "3D" view from the lower right corner. It should load 3D models of the buildings. Then if you hold Control which clicking and dragging, you should be able to freely rotate your view around the map's center point and see the buildings from any angle.
EDIT: and I should mention, it works all over the place, not just cities, i.e.: https://www.google.ca/maps/@41.0775591,-71.9351097,67a,20y,2...
This would make sense as it's based on Google Earth which is 3D.
Even WebGL web version of Google Maps is already 3D since some time ago. See e.g. Colosseum here:
https://www.google.com/maps/place/Colosseum/@41.8950247,12.4...
From what I saw in demo, it looks like they are generating simple 3D models from the photos. Which is pretty damn cool!
Here is an interesting quora on where Google Earth sources their models from: https://www.quora.com/How-are-the-3D-models-of-buildings-gen...