I bought this edition (and yes, you should probably read the 4th edition, not this one) in the early 1990s when it was fairly new, and read the first seven chapters. I learned so much from those chapters that I stopped to do some parallel reading; and, well, you know how that goes. In the meantime, this volume has surely gone out of date -- even the 4th edition is a dozen years old now, for crying out loud -- but I recently decided to press through to the end, even though this isn't the latest information.
The value of reading an old text like this isn't the freshness of the information, it's the discipline of studying how a broad summary of a field is done. My amateur's exposure to archeology is single-site report by report, or paper by paper, and that makes the Big Picture elusive. A book like this (and they are all too rare in any science) takes on the task of saying: This is what we know, and how we know it; this is why we know more about stuff over here, and almost nothing over there; this is what we don't know, but might figure out if we looked for it; and this is what we've been doing right, and this is what we've been doing wrong. I noted Cunliffe taking his senior position in the field to chide his colleagues for failing to publish their dig results. [That is a HUGE problem in archeology and paleontology. Folks do digs for a season or more, then spend their entire remaining years sitting on the data. Only a small fraction of the "information" that archeologists have acquired has been systematically published -- which pretty much means it might as well still be in the ground.]
So, for me, this volume will have as much impact on my fiction writing as on my understanding of the subject matter. Cunliffe is excellent at drawing the line between what we suspect may be true, and what we can actually accept. I particularly admire his awareness that radio-carbon dating for the Iron Age is essentially useless, except to define which millennium a site is from. He has an appendix listing every single date they've got, but he doesn't cheat and use it in his discussions as crucial data, because it isn't.
The historically illuminating information in this volume is the revelation of the effect of the Roman civilization well beyond its borders. You can see the approach of the Roman economic system into Southern Gaul in the artifacts and settlement pattern changes in Britain, which is several hundred miles and the English Channel away. Then you can see the dramatic changes when Caesar brings all of Gaul into the Roman sphere, and again when Claudius takes over Britain.
My favorite detail from the whole exercise is his observation that, "At the beginning of the eighth century (he means BC) the Eastern zone was experiencing an intensification of the belief systems which led to the deposition of bronze. Bronze was taken out of circulation and either buried in hoards or thrown into rivers." I love that sharp connection between a belief system and a change in artifacts.
This is one of those magisterial works that remain relevant in the history of science, long after the science itself has moved on. I'm glad I bought it when I did, started it when I did, and finally finished it.