This is a great app and I'd recommend getting it. Unfortunately, the whole world isn't 3d, but that makes sense for multiple reasons. For one, most of the non-3d areas are random countryside's or small towns, which makes sense, as it would take so much effort to turn a tiny little town in the middle of Canada to 3d, and it's not worth it. For two, places like China, Russia, and North Korea obviously aren't 3d because those countries dont give us permission to analyze there country at every angle thousands of times (for good reason). Overall, it's amazing, and I fully recommend it to any geography or history nerd.
One thing that would be cool is adding a function where you could change the time of day. For example, you could set it to midnight setting, and everything would be dark and windows would be glowing. I don't know how the Google satellites work, so it might not even be possible to add a day/night setting with our current technology.
Anyway, that's my review!