I like Flickr for the 1 TB of free space they give. It has replaced iPhoto for me; I would rather have something portable that is free.
As for the app, auto sync, organization, individual photo settings, and editing are great. Now that videos are auto-synced, this is the only app I need to keep my memories backed up to the cloud. Why pay Apple for more storage when Yahoo gives you similar functionality for free?
I love that you can now select multiple groups to put a photo in.
Sack_Sama about Flickr, v4.3.0