I'm very excited about this release. CoreOS, Docker and etcd are a great fit for one another. I love the separation of concerns that is provided.
IMHO, the weakest part of CoreOS is fleet (https://github.com/coreos/fleet). Compared to the other components in the stack, it just feels very inelegant. The systemd configuration syntax is complex and ugly. I wonder if there will be work invested to upgrade fleet to something that is as elegant as e.g. etcd/Docker/CoreOS itself.