The Free Software Foundation-supported Linux distribution gNewSense is finally out in its fourth revision after a two-plus-year development cycle.
The FSF is best known for its unrelenting advocacy for software unencumbered by patents and protected for future use by the GPL, as embodied in software like the Linux kernel and the GNU toolchain. The gNewSense Linux distribution is assembled with the FSF's goal in mind of having no dependencies at all on proprietary binaries or other components that aren't compatible with the GPL.
The base of gNewSense is the Debian distribution, which already excludes proprietary binary blobs and unfree software but provides access to them via repositories. But gNewSense goes further: It doesn't even include access to such software in its repositories. Its documentation also includes only material that's compatible with the GNU Free Documentation License.
Earlier gNewSense releases used Ubuntu as the base, but the project switched to Debian (from which Ubuntu was derived) because it already performs a lot of the work needed to remove GPL-incompatible elements.
When every piece of software used in the system is fully open source, nobody has to fret about patent or copyright issues. There's less worry about this topic than there used to be, though, thanks to groups like the Open Invention Network, companies like Red Hat offering indemnities to their paying customers, and a general shift in perception about free and open source software.
Unfortunately, gNewSense's purist stance is also its biggest disadvantage, since many hardware devices -- some network cards, for instance -- have no nonproprietary drivers available and thus won't work with the distro.
Another disadvantage is that many applications provided with gNewSense aren't the most recent versions. For instance, though Linux is into the 4.5 revision of its kernel, gNewSense still uses the 3.2 kernel, as well as the highly out-of-date LibreOffice 3.5. (The program is now in its 5.1 revision.)
This last issue may be more a matter of how the distribution itself is assembled and maintained, rather than its underlying philosophy. Several other distributions, such as Trisquel, Blag, and Dragora, use the same guiding philosophy, but with more recent versions of apps. Trisquel, in particular, uses LibreOffice 4.2.3.
[Edited to clarify that the FSF itself does not produce gNewSense, but simply supports the project.]