Let me just say that the translation, as the other review on this page suggests, is not great at points. I can't read Italian, so I've hardly got much of an option, but one imagines when reading this that it could be better. Versus other books in this series that have been translated from Italian (I'm thinking here of the absolutely wonderful The Making of the Indebted Man by Lazzarato), it doesn't quite hit the spot.
That being said, I disagree with the one-star rating. Marazzi is a wonderful thinker, as he's already shown in his previous substantive works. If you can stick with it--the book (and translation?) definitely improves as it goes along--there is much to be gained from this.
Though it is tough at times, Marazzi really picks apart the logics of financialised capitalism in a remarkable way. Although he isn't alone on this front, he does a great job of trying to move beyond the notion that financial capitalism is somehow 'parasitic' on a 'real' economy (an economy that produces material objects and goods). Rather, as Marazzi traces, financial capitalism is a change in the valorisation process. That is, reworking Marx's thesis, valorisation (the process of value extraction) no longer occurs at the point where goods are produced and labour is undertaken, but it now takes place in the realm of circulation. He is only too aware of the human and social consequences of the changes, and draws upon theories of biocapitalism and his fellow autonomist thinkers to articulate this.
The afterword is a concise response to the crisis that we see today following the 2007/8 financial crash. Marazzi rebukes the theorists who see Keynesianism as an obvious way out (Krugman et al.) and looks for ways out of the mess that it in itself an integral product of the grotesque system of financial capitalism.
4/5 stars on the basis that a) the translation could better, as above, and b) Marazzi is still better elsewhere (see Capital and Affects). That being said, as a worthy addition to Semiotext(e)'s fantastic Intervention series, it more than holds its weight.