I read William Cohan's Goldman Sachs book with pleasure and profit, but if you haven't that kind of time, you might want to take a look at the piece on it by James Macdonald in the London Review of Books. Coyly I don't call it a "review," because it is really more of a précis. But a good précis it is and might save you some time.
Aftertought: I haven't read Macdonald's own Free Nation Deep in Debt; not on the Kindle. Palgrave, are you listening?