Minima Moralia consists of loosely connected meditations and ponderings on society and culture. Adorno was clearly an incredibly perceptive mind, and these rueful meditations observe how the wider forces of capitalism creep into the minutiae of our lives. Adorno laments the brusque and utilitarian quality of door shutting, the demise of the French brothel, as well as making broader digs at targets like revolutionary communism. Minima Moralia, and this is probably the best compliment you can pay so called critical theory, is a provocative and quite depressing work, showcasing Adorno's seemingly endless disgust toward life in capitalist society. I'd say it ranks with the works of other great provocateurs like Nietzsche and Foucault, doing the Socratic job of making us uncomfortable about how we are living our lives.
Minima Moralia is also a nice companion volume to Adorno and Horkheimer's more widely read "Dialectic of Enlightenment". Adorno's thinking is more relaxed and concrete here, showing his talent for a telling story and a wry observation. You could, rather simplistically, read Minima Moralia as a catalogue of the sort of observations that led to the Dialectic's grand theses about Enlightnement and modern reason. For those like me who found the Dialectic infuriating, this work gives you some insight into what led to Adorno and Horkheimer's rather baffling claims.