In the Free Software Foundation's May 2013 review of single board computers, the Raspberry Pi was found to have fatal flaws for use in a free (libre) software environment:
The Raspberry Pi requires nonfree software to start up. It can't reach the point of executing free software unless this nonfree program is part of the installed system software. ... This nonfree startup program affects both models of the Raspberry Pi.
The Raspberry Pi Zero was also not usable without proprietary (nonfree) software.
Is the new Raspberry Pi 3 usable without the need for any proprietary (nonfree) software?