Not to mention the fact that because intermediary containers are imaged, you don't have to worry about making a mistake in your script.

Sometimes (okay, every day) I find myself trying a bunch of different things to get something to work. With Docker, you've got a series of "save points" along the way. You can continue building an image from the last good point, and end up with a really clean image that represents the shortest path from bare install to "what I need to get done."

I was playing around with a Perl script about a month ago that would strip all the RUN statements out of a Dockerfile, convert them into a shell script and use that to bootstrap a Vagrant box. So what I'm saying is, if you don't know what you're doing (or just like to experiment with OSes), Docker is really interesting.