We've been using Docker as well and I can attest to the shear number of bugs and constant regressions. I don't think a release has gone by without a bug that prevents us from updating. From slow pulls, to slow extractions, to issues with SELinux, to namespace incompatibilities, to the daemon just hanging repeatedly. It's frustrating because the technologies around Docker (Mesos, Kubernetes, Marathon, etc) seem to be getting better and more stable while Docker just continues to have issues.