[3amOpsGuy]

It offers a reduction in the time to get started; vagrant provides the wrapper script around vboxmanage that you would otherwise write & debug.

By effectively standardising that tool which many people would otherwise continually reinvent, the group as a whole benefits from sharing and moving things forward, e.g. The many pre-packaged system images, puppet config examples and the like.

If you're not using it, I don't think you'd be missing anything worth losing sleep over.

I looked into it a while back - I saw it as a potential way to save my time documenting our setup for others, but in the end I opted to make my own as we have other tools to be integrated with, and by doing it myself I didn't cost myself any extra time really. I would have had to adapt either vagrant or our machine provisioning setup which would have taken more time than writing a very thin wrapper over vboxmanage.