I can tell you what attracted me to Docker as an early adopter (while @Mailgun): * Very good user and developer experience. Docker felt like git for containers

I can tell you what attracted me to Docker as an early adopter (while @Mailgun): * Very good user and developer experience. Docker felt like git for containers. Docker run, docker ps and other commands are awesome. * Very good and innovative build system. Dockerfiles are great and allow to build complex containers and efficiently package software in a convenient way. * Solving image distribution problems. Docker pull/push are great. * Layering system leading with build and run optimization. Overall docker not only provided a great UX, but combined all the patterns above in a very expressive system, great job done by the team.