pkgin is aimed at being an /apt / yum/ like tool for managing pkgsrc binary packages. Many so-called GNU/Linux distributions provide a convenient way of searching, installing and upgrading software by using binary archives found on "repositories". NetBSD, and more widely, all operating systems relying on pkgsrc have tools like pkg_add and pkg_delete, but those are unable to correctly handle binary upgrades, and sometimes even installation itself.
This is the purpose of /pkgin/, to provide the user a convenient way to handle binary packages, using the same working mechanisms than tools like /apt-get/.