In my opinion it's way better then submodule or svn-externals. Basically it allows you to take an specific folder from your repository and push only this folder

In my opinion it's way better then submodule or svn-externals. Basically it allows you to take an specific folder from your repository and push only this folder to an additional repository. This repository could be included into another repository which makes sharing code between repositories very easy while keeping history in each of them and the history for this special folder in an extra repository.