Some real classics here, particularly Joanna Russ's "When It Changed." Pamela Sargent's intro gives a good overview of what was going on in SF at the time (1970s), but can be skipped w/o any loss of appreciation of the contents.
The first story, "Screwtop", was probably my favorite of the collection. It read like it could have been part of a larger work - like there had been other stories set in the same world, or featuring the same main character, but thus far I haven't found any related works. It's set on a world where prison labor is employed in dangerous mining jobs, to produce energy for the ever-increasing needs of its population. Some of the prisoners we "meet" aren't strictly criminals in some cases, but rather individuals who have rejected the life path set for them by society. The overseers take full advantage of their positions, sometimes capriciously doling out both punishment and reward, and using their power to manipulate prisoners into doing their bidding.
"The Heat Death of the Universe" is told in alternating sections of scientific facts and comments on the life of one woman, Sarah, who has left a career in physics and spends her time tending house and raising her children (although exactly how many children she has is unclear, even to her.) Although her reflections on how her life has changed are often funny, there is an underlying and growing sense that all is not right, and eventually her thoughts and behavior become disturbingly bizarre.
"The Warlord of Saturn's Moons" is an entertaining glimpse into the head of an author as she follows the exploits of the characters in her space opera. "Songs of War" tells the story of an army of women, brought together by shared dissatisfaction with their societal roles, and the conflicts that have torn apart many revolutionary struggles. "Debut" is another disturbing story in which women and men live entirely apart. "Building Block" is about an architect whose valuable and visionary building plans have gotten "lost" due to memory loss, and her attempts to recover them prompt people she has trusted to take advantage of her. In "Eyes of Amber", a probe from Earth is mistaken for a demon by an outlaw on another planet, and the scientists monitoring it are aided by a musician in communicating with her.