So much of what is written about the period 400-600AD focuses on whether or not King Arthur and his merry bad of knights ever lived in downtown Camelot. A lot of what is written is lovely and romantic and if it isn't true -- then it ought to be, as Winston Curchill once said.
It doesn't always help if one is trying to grope towards some kind of understanding of the process by which Late- and Post-Roman Britain ended its links with Rome, and how it came to be Anglo-Saxon England. Which is where Age of Tyrants comes in.
It is destined to beomce the standard work on this period, and rightly so.
All the old questions: Continuity or change, immigration or elite-takeover are still there for the asking.
Hopefully DNA analysis should eventually begin to help us sort some of them out, but what Snyder also does is point out the sometimes woeful state of cataloging and publication by archaeologists, not helped by lack of funds devoted to this. This means that we aren't always able to interrogate the data we do have properly - never mind go looking for more sites to dig up.