This book clarifies much of Foucault was saying in History of Sexuality. Butler is careful, however, to not borrow the models Foucault uses, thereby, avoids some of the mistakes and gaps that occur in his thinking, namely the silence on women. Butler, more than Foucault, is not willing to settle the debate on sexuality merely as the obtaining and disseminating of pleasures and how those bodies perform them. Rather, she takes bodies as always already gender indeterminate and destablilizes their performatives further to show how bodies are marked by gender as well as race, class, sexulaity, etc. and how these categories are also destabilized within the perfomative. I highly recommend this book to feminist and queer theorists and well as anyone who is concerned about creating any sort of opposition to the reactionary right-wing forces that are attempting to further entrench their dominance over the rest of us.
When Judith Butler describes gender as performative, contrary to much of what is mistakenly thought out there, it is not about choice! It is not about choosing to put on a gender--as if it was a performance in the traditional or obvious way. The performativity of gender is meant to suggest--invoke--that gender is constituted by performative acts which repeated come to form, take shape, a "coherent" gender identity. Thus, Butler uses the performative to suggest that this coherency is false and that because of acts that disrupt the strict reads of gender--acts that occur naturally, perhaps daily, perhaps unacknowledged, gender comes to be seen/viewed as that which is only as stable as this performative function's stability is. Or put more simply, gender-as-stable is undermined by Butler by reading it through the performative--becuase it is never "performed" the same exactly. So, it is not that people can choose to perform a certain enumeration of gender, rather it is that noone precisely (actually) fulfills these gender identities that we have!