Using it every day, all our CI/CD flow is built on Docker containers, with Wercker, Tutum (and now DockerHub, Wercker's support for Amacon ECR came a little bit late for us), Amazon ECS.
Performance tuning in prod has sometime been a little bit challenging, but the constraints are really worth getting into, as soon as we also consider how much benefits we get from it (we make sure our Docker images' tags correspond to git sha1, hence with the task definition of the service it's a no-brainer to get the exact code that is running on any given stacks, just to give a small example. Dependencies, easy to stop/(re)start, are other obvious wins.