Couple of pointers after wasting a lot of time in the official support community.
Free tier optimize all images and videos.
Paid tier use storage for all images and videos.
Face Detection is a US Only feature right now.
No support for comments, +1s.
Sharing is only based on links. No account is needed. Anyone who has access to the link can check your shared content.
You can disable shared links. But you cannot track who has access to those links or who accessed your content.
People with access to your shared links can add that content to their own
Google Photos with a single click.
Auto Enhance is now manual. Auto Awesome still exists. Lots of effects appear to have disappeared.
There is still no deduplication.
There is still no collaborative albums.
There is very little information about photos shown.
You cannot edit any EXIF data about the photos. You cannot tag images. You cannot caption images. You can however describe images.