As a developer it's great. I solves the.. I need a <Mysql, redis, zookeeper> to write code against. So instead of spending my time learning how to be a sysadmin again it lets me focus on other things that matter more (to me at least).
As sysadmin it also lets me sandbox things. Does have a bit of a performance hit, but instead of trying to figure out the various python libraries needed to get mailman running, or any app you can just run it in a container and when you're done your base system is still stable and not polluted with all the crud. Of course it introduces its own set of issues into the mix.
RE: Docker IPV6 Guide