Disappointing, esp. after reading a masterpiece like Discipline and Punish. This book consists of a serious of loosely connected, and individually incomplete meditations on various topics, that are intended to serve (not very successfully, imo) as a prolgomena to a history of sexuality. Indeed, the project was abandoned (what was eventually publishd as vols. 2-3 was part of a newly and differently conceived project begun several years later), proving that the current work was a failure.
It should not have been published, and one can assume that MF may have felt the pressure to come out with another book fast to capitalize on the success of D&P.
Parts I-III contain suggestive hints on the relation of sex in the formation of the Self (whereas for Freud, the ego is constructed at the boundary between desire/id and reality, for Foucault the Self is constructed at the boundary where superego (i.e., the administrative gaze of Power/Knowledge) inscribes itself upon the body. This is a brilliant conception, and a fascinating answer to the inherited problem of the transcendental ego, but it is really only adumbrated in these chapters.
Part IV deals with method, and is long and dull, and can be "skimmed".
Part V then takes the topic of sex in the direction of MF's new interest in biopower, which was then the topic of the Collège de France lectures of these years (1976-1979), before he turned back, at the end of his life, both in the lectures of 1981-1984 and in vols 2-3 of Sexuality, to the problem of the constuction and the hermeneutics of the Self -- a topic that Dreyfus-Rabinow also discuss in detail at the end of their study...