I've been toying around with Kubernetes (AKS on Azure) the last few weeks and have to say I rather impressed. Still being able to start from scratch and be up and running in one hour is really impressive.
Clusters come up faster. They're easier to upgrade. Don't have to delete clusters to change them (just provision a new node pool). Persistent storage is less weird. No RBAC. Weirdness around kube-system namespace. I.e. if I create a registry there, it gets disappears with no logs or events suggesting why.