Pop Quiz CTL what service has 1/2 billion users? Go to the head of the class if you guessed Google Photos. Google is self declaring that this is your photo app of choice. And I agree with them for the following reasons.
- Drop dead easy to use.
- Unlimited free storage with a google account
- Sharing is a no brainer
- Making movies is very simple
- Backup is automatic.
There is a great article about Google Photos here