Google Earth has never been too highly publicised, besides maybe a couple seconds in a Nexus tablet commercial here or there. A lot of the awesome use cases for Earth have also been slowly integrated into Google Maps. Maps is new and stylish where Earth feels antiquated, Maps is light and fast where Earth is slow and laggy. Hence, Earth hasn't had wide appeal, especially when Google showered Maps, its prodigal son, with attention.
Google has finally shown Earth some love with a significant update for Android. You can see the change right from the get-go, as the icon has been redesigned to fit in with the material guidelines.
The 3D technology in Earth is getting its first major upgrade since the launch of Earth a decade ago. This will result in sharper views, as well as smoother and faster 'zooms'. Google Earth will now get the same updates as Google Maps, so you will be viewing the newest information and imagery. Further, the roads and labels have been redesigned to better blend into the terrain and make viewing more pleasant. Lastly, if you've made your own Map, you can open them directly from Drive inside the Earth app.
There is nothing revolutionary, but everything about your experience is being refined. It promises be a pleasure to use, and provide a much easier workflow for the more involved users creating their own maps, thanks to Google Drive support.
The update (read Google's blog here) will be rolling out in stages, as always - so practice patience if you don't have it yet, or download an APK from a source you trust.