This is awesome. I didn't realise OSM even had such detailed data on building shapes. As others have noted, outside (or on the outskirts of) major cities the data is quite sparse but central London, for example, looks great.
Yeah, the OSM data seems really complete for some cities. Co-incidentally, I've recently been putting together some 3D GIS visualisation stuff using OSM data.
Try zooming in to pretty much any capital city, then use the right mouse button to rotate the viewpoint so the 3D shows up properly:
As a data point, holding down the shift key + using the arrow keys at the same time also works for moving the camera viewpoint. It's not as fine grained as the right mouse button, but it works "well enough" as an alternative for setups without a right mouse button. :)
