Apple has made it easier to view which cities have 3D buildings. In the above image, you can see the rounded black on white circles next to cities with the labeled, “3D”, signifying that these cities have 3D imagery built into the map.
When tapping the 3D badge, it gets replaced with the familiar white on blue icon with 3D buildings. Another example of further refining the data presentation to the user.
Stills from above