Google Photos 4.0, rolling out today, introduces Material Design 2.0, though the changes seem to be primarily superficial, and are completely in line with what we've come to expect from Google's design language.
Aside from the bolder colors and rounded corners, however, the latest Google Photos update also introduces a neat new gesture that allows users to swipe up on a photo to reveal information about it. It's great when it works, but as Android Police notes, it often times doesn't pick up on swipes accurately. This is something that will likely be patched up in future releases.
Google Photos 4.0 is now rolling out on the Google Play Store, though it may take a few days to become available in your region.
source: Android Police