Vagrant is the execution environment that you set up, share and whatnots. Your dev environment (IDE, text editor, etc) can still be in the original environment you are familiar with.

For example, just yesterday, a colleague wanted access to Fork the Cookbook's source (he was supposed to be helping out on frontend javascript). But because some bits of the code is written to be Linux specific, he needed a Linux box while working on a non-Linux box.

So I spent 30 mins creating a Vagrantfile, specifying the environment which Fork the Cookbook runs in. He takes it, runs the env, provisions with the existing provisioning script, and tadah, you get an environment where you get to run the code in.

Due to the synced directories, you can code in whatever env you are hosting on: it's like dropbox between your computer and the virtual box. Network pass throughs allow your host (i.e your physical machine) to use networks defined virtually in your virtual computer.

Great for sharing execution env and getting other people started. Not really necessary if you're working alone IMO