On the one hand this is an invaluable chronicle of many of the most ridiculous things human beings have got up to in European history.
On the other hand it leaves a lot to be desired: Macky is interested only in describing. Though he does have the odd snide comment, he is not interested in "the why" at all, and perfectly willing to ascribe it to folly / original sin (or whatever you want to call it). If he published this today, he would get ripped to shreds for not trying to understand the nature of these things.
Just describing would be okay if he were a great story teller - and modern critics would be kinder too - but he's not. And so it is hard to praise something where literary merit and analysis are both missing.
Another issue is his selection: included in these popular delusions are phrases; I'm not making this up. Certainly human mania for catch phrases is on another level than human mania for witch hunting. And if it isn't, he really should make the connection for the reader.
So while this is worth reading for historical interest and definitely for the purposes of writing a new, better type of compendium of these sorts of things, it's not really the classic its made out to be.