Terrain View isn't exactly new as far as Google Maps goes, since it's been there for quite some time on the browser version of Google Maps. However, it was noticeably missing from the Android app version. At least until now.
This new view mode might not exactly be useful for commuters or casual users, however, it can be quite essential for trekkers and adventurers. Terrain View gives a topographical 3D rendering of an area, showing land details such as mountains, canyons, and the like, alongside the usual roads and hi-ways. It also has markers that note the elevation of land, giving users an idea of how high or low these areas are. Potentially life-saving, not to mention time-saving, information, and its a bit of a wonder that it took this long to have the feature inside our mobile devices where it could be used best.
As always, staged rollouts means it could take time for the update to arrive in your region. Unless you're an extremely mobile and well-traveled user, waiting is probably not going to be much of an issue.
Download: Google Maps on Google Play Store