This is the first book to present a synthetic view of Roman banking and financial life from the fourth century BC to the end of the third century AD. It describes the business deals of the elite and the professional bankers and the interventions of the state. It shows to what extent the spirit of profit and enterprise predominated over the traditional values of Rome, what economic role these financiers played, and how that role compares with that of their later counterparts.
So... I mostly read this hoping there would be discussion of Caecilius. And while he was mentioned, there was much less reference to him than I had hoped. There's lots of information about argentarii (and other figures of the financial world, with lots of text differentiating them all) in general, but sadly, the chapter about some tablets of records from Pompeii was actually about some other banking family/group. I realize this means I should probably read the author's book about Caecilius specifically (but it's in technical French and I had enough trouble with all the economic/financial terminology in this generalist book in English!). Anyway, argentarii worked on small-scale things (relatively), which the elite and their agents worked on large-scale things. One of their chief things seems to have been to act as intermediaries at auctions, where the argentarius paid the seller immediately on behalf of the buyers, and then advanced the buyers credit to pay off what they have bought on a term of several months to a year. They could also hold deposits, both regular/sealed deposits (where they were not to be opened/used by the banker) and deposits that could be reinvested by the banker. They also of course did money-changing. Some may have given maritime loans (which are different from most other kinds of loans, because they were secured by the ship/cargo; but if the ship/cargo was lost, the loan did not have to be repaid; they had very high interest rates). Many of those involved in banking/financial stuff were slaves and freedmen; the children of argentarii did not usually carry on the family business (Quintus would not, even though his father had).
Anyway, the book is readable, but more narrow in focus than I would've thought, given the title. There's lots of uncertainties, but Andreau does a good job at delimiting what is consensus from what is his personal opinion and attributing various opinions to their proponents.
He also engages with the modernist v. primitivist debate on the ancient economy, but he seems almost as reluctant to write about it as I ever am to read about it.