This is a handy book of secondary if you're interested in the structuralist, poststructuralist, and broadly feminist ideas of difference (and differance!). It's clear and concise, even when discussing writers like Derrida. However, I did find that it lost some of its clarity in the last chapter, which discusses very contemporary figures such as Badiou, Zizek, and Butler.
Overall worthwhile, and recommended to those who are interested in structuralism and poststructuralism.