Growing up, I learned about the work of Bishop James Ussher of Ireland mostly in a mocking way; he was "that fool" who counted the years in the Bible and came up with a creation date of 4004 BC. Through high school and college, this was the narrative I received.
A few years ago, I was surprised to see
the book available in new translation, and to learn that for decades, there had been no readily available version of it in English--and not too many places had a copy even in Latin. Hence, the critique I received was mostly a "hatchet job," criticism by professors who had never read the work quoting what they'd learned from their professors who had never read the work quoting....you get the idea. If you didn't read Latin, you hadn't read the work, and my professors weren't trained in that language.
Learning this, my family obtained a copy of the new translation, and I've been wading through it for a few months. Far from being only a justification of a young earth, it's rather a summation of the history of the world (as Ussher knew it), drawing from the Scriptures and ancient historical works--Livy, Josephus, Cato, and so on. With the limited resources available to him, Ussher's history is really a summation of the history of the Mediterranean and Middle East from "the beginning" to the early Christian era.
It is a very difficult work to read, even in translation, as Ussher does not attempt, as modern historians do, to form a "narrative" that guides the work. Rather, Ussher divides history in to a series of thousands of events and sub-events described by the ancient historians, and he compares and contrasts the reports of one historian versus another. The translator moreover makes occasional notes about where the Loeb editions of these works (which have the same manuscript issues any other ancient text will have) differ from those which Ussher used.
By concentrating on the big events, rather than forming a narrative (a theme that really only started in the late 19th century, more or less), one will learn quite a bit about the kings, caesars, imperators, and such, but you will not learn a whole lot about the lives of the common people. The book discusses a bit of the technologies used by the people (mostly of war), but all in all, Ussher covered what the ancients wrote, and that was the deeds and exploits of the kings.
Which were, apart from some minor good examples, mostly wretched, consisting in betrayals, adulteries, rapes, wars, and even murders of one's own children for the sake of political gain (Cleopatra and others). The book also details the places where the ancients disagreed--making very clear that if history is anything, it is messy. Just because one authority mentions something doesn't mean others agree, to put it mildly.
As such, it's a good work for those with good endurance in reading and a bit of maturity in reading history. Those who don't like to read will struggle mightily with this one, and those who want history to be simple and easy won't like it, either. However, those who have a touch of endurance and maturity can benefit greatly by struggling through this work.