I've checked the Android section from Google Dashboard and noticed the difference between Nexus 7 running Android 4.3 and Nexus 5 running Android 6.0. While Nexus 7 only backed up system settings, the wallpaper and some data for Gmail, Google Calendar and Google Keyboard, Nexus 5 backed up the data for almost all the apps: from QuickPic Gallery to MyFitnessPal, from Firefox to Opera Mini and Angry Birds 2. There are still some apps that don't support auto backup, but at least the feature is now opt-out instead of opt-in.
The Android section from Google Dashboard shows a lot of useful information about your Android devices (IMEI number, registered date, last activity date, carrier) and it also lets you delete backup data. "Please note that new backup data will be created if backup is enabled on any of your Android devices," informs Google.
The list of apps backed up to Google Drive is also available in the Settings section of the Google Drive app for Android. You can enable or disable the backup feature, automatic restore, reset network settings, add backup accounts. The nice thing is that all this data doesn't use your Google Drive storage quota, but each app is limited to 25MB.
"Apps running on the new backup system aim to save their data every 24 hours, but there are a few requirements for the backup system to trigger automatically. The new backup system uses the JobScheduler API introduced in Lollipop and only triggers a backup if the device is connected to power, on Wi-Fi, and has been idle for at least an hour. The data then gets encrypted and uploaded to Google Drive," reports Ars Technica.
It's worth pointing out that reinstalling an app from the Play Store restores its settings and data. This way, you won't lose your data when you uninstall an app and you don't have to reconfigure an app you've previously used. In my opinion, this is a game-changing feature.
The new backup service is powered by Google Play Services, so it can be improved without updating the operating system. Hopefully, Google will allow users to disable backup for certain apps, remove the 25MB limitation and backup even more data.