It's difficult to be too critical of a book that only costs $2, but this does feel like rather a lost opportunity. To begin with, while the book does (as its ad page says) have 18 pages, only six of those pages actually contain content - the other 12 being artwork-only, adverts, the title page, etc. And 6/18 is not a great proportion...
The book covers five professions, all but one of which are concerned with metalwork of various kinds. Given that it is intended to be a design tool, a clearer idea of what kind of craftsmen are likely to be in a community, and what the full range of crafts is, would have been helpful.
Instead, you just get a brief description of what, for example, an armourer does, along with some advice that's mostly fairly obvious (For example: 'arsenals run by people from specific cultures are likely to produce items associated with those cultures' - well, yeah...)
Having said that, the book does contain some useful information, but even that tends to be lost in the effort to be general, and apply to all settings. There's only so much you can say when you have just one page to describe all armourers everywhere!
So, yes, the book is only $2, and one doesn't expect a magnum opus for that sort of money. But the book is still not as good as it could have been, and, for that reason, I can only rate it as 'average': it's pretty much what you'd expect if you're not really paying anything.