I have all the books in this series, and they are all well written, and squeeze as much information into this sized book as possible. If you want more information, get Britannica; otherwise if you are just looking a a fairly in depth description of the different campaigns that Rome waged, this should do.
For an idea of how in depth these books are, this one on Greece and Macedonia gives a considerable amount of information not just about the campaigns, but about the complex conditions of the people being invaded, and what their motivations were. Each book is unique, and one of the things that makes the time period of this book so is that Rome had not become the juggernaut that history reflects on them as. At the point in history that Rome was still bringing Greece into the fold, they still hadn't subdued Carthage and Hannibal was still running around Italy with elephants.
The only reason i didn't give this 5 stars was because it could have had more maps. But that is partially just laziness, because there is enough detail in there to draw your own map.
So far all of the Pen and Sword books i have purchased have been well written, and they are all printed in England.