You're right that it is not a usable virtualization solution... because it is not a virtualization solution at all. Docker is a dependency management tool. To the extent that you're using virtualization for dependency management then Docker is an excellent alternative due to its lower operating overhead. If you're using virtualization for resource allocation and management, then Docker is not such a good fit. As someone who has used it quite a bit over the last six months I bristle a bit at the suggestion that it is merely a "PR engine," by which I assume you mean "something that isn't really new or useful but that garners a lot of attention." Not an accurate observation at all, in my opinion.