Newbie question: How does quay differ to docker hub?
For those that use LDAP authentication for this, it makes is a much smaller attack vector.
The per-team "organizations" is very nice and allows you to give teams their own flexibility while still running things within your own firewalls (on-prem or in a vpc). It is an alternative to docker hub with a lot of really nice features.
The ability to do scheduled mirroring of images from other registries (such as docker hub) and replication between different instances of quay is also really beneficial.
Disclaimer: commercial quay enterprise user for some time.