Debian GNU/Hurd has been in development for years, but still has not been officially released. Roughly half of the software packaged for Debian GNU/Linux has been ported to the GNU Hurd. However, the Hurd itself remains under development, and as such is not ready for use in production systems. Most Debian users run Debian GNU/Linux, rather than Debian GNU/Hurd.
GNU can be tried out using a Live CD.