Out of all the seven deadly sins, avarice is probably the one that motivates the typical adventurer the most. Killing things and taking their stuff is, after all, a fair description of what avarice is all about. So, even were it not for the alphabetical sequence of this series, avarice would have been a good place to start.
There is some brief description of avarice and why it's a bad thing, including a two-paragraph cautionary tale set in the Free City of Zobeck. But that's rather incidental to the purpose of the book, which is to describe four monsters on the theme of the titular sin.
Ignoring the cover, contents and licence, the book is 6 pages long in total. The descriptions are one page each, including the stat block and a fairly large piece of (good quality) art. So, basically, the sort of thing you'd get from a Monster Manual entry, rather than an in-depth discussion... but, really, that's all you need.
I give this product the full five stars, partly because the production quality is unusually good for the price, but mainly because the creatures are well thought out, and that is, after all, the point of the book.
They have a good range of CRs, from 1 to 20. Most operate by tempting an adventurer's avaricious nature, but they do so in different ways. The mimic from the MM is a classic example of this kind of thing, and, indeed, there's a variant of it here that works well alongside the standard version.
On the whole, four rather good monsters, succinctly described and linked by a theme that's somewhat relevant to dungeoneering. For the price, I'd recommend it.
[5 of 5 Stars!]