There are at least three other books with the same title. There are also a host more from various other historians and/or archaeologists covering the same topic: Roman Britain. I have read some of them, but by no means all of them so I am in no position and do not intend to make sweeping comparisons. It may not be perfect. I found a few "glitches" in it. Some things looked a bit odd, or perhaps even a bit questionable, and I will get back to these later on.
To begin with, the reader needs to understand what the author seems to have tried to achieve and how she has - quite deliberately - limited herself to what is really known. This is what you would expect any good historian to do, although it can be quite difficult and it raises at least two sets of issues.
The first set of issues arises when realising how little we really know about "Roman Britain" and how much we have to rely upon comparisons with other parts of the Empire, some of which may not always be relevant. This is something that is very well shown and illustrated across the book. A related point here is that the main advances in Roman history in general, and Roman Britain in general, are due to archaeology and the numerous findings that have been discovered. However, even in Britain, where archaeology started earlier than in most places and where there is still some much to find, there are limits to the information it can provide. This is also something that the author shows rather well and she mostly refuses the kind of unverifiable speculations and theories that could have so easily side-tracked her.
For this in particular, the book and its author deserve quite a lot of credit, especially since it can easily lead to misunderstandings and disappointments. For instance, a reviewer of the Kindle version of this book complained that it was "a history of Roman Britain written entirely from a Roman perspective." This is a perfectly correct statement. It may even be exactly what the author intended to do although whether intended or not, there was simply no alternative, given that the facts about the Britons (that is the collection of tribes that populated the island) are even fewer than for the Romans. The conclusion is that it is simply not possible to write a history of Roman Britain with "insights into what the indigenous population did or thought". Consequently, it seems rather unfair to blame the author for not having tried to do something that is simply not possible.
A related criticism is that this book has an "almost exclusive focus on military affairs." The statement is perfectly accurate. Whether this should be seen as a criticism is perhaps more questionable. Patricia Southern has written extensively on the Roman army. This book reflects this fact and even includes bits and pieces from her more general volume on the Roman army, with a number of examples from the Roman Army in Britain being found in both volumes. There are also two other reasons explaining the focus on military affairs and the Roman Army. One is the fact that the Roman Army is perhaps better documented, and the other is that it played a huge and complex role in the development of Roman provinces in general, and Roman Britain. Both reasons are well and rather convincingly explained in the book.
Apart from its obvious "law and order" and strictly military role, it also played a considerable economic role. Provided for Roman forces was a huge market, or more accurately a series of large markets in each of the provinces were significant forces were stationed. The economic role of the Roman Army was also indirect. Many of the forts that were evacuated as the army moved to the north became the sites of Roman towns and Roman engineers did occasionally help edify public buildings, for instance.
Two further advantages of this book, for a so-called "general reader" or someone not very familiar with the history of Rome, and of Roman Britain especially, are the way it is written and the structure that Patricia Southern has chosen to follow. The contents are presented as simply as possible, that is chronologically. A number of boxes are scattered across it to explain and focus on specific points. The text itself is indeed presented as a matter of fact way, using plain layman English, with explanations and translations being provided as soon as a "specialised" or Latin term is used. As a result, the contents are clear, easy to access and easy to understand.
There may however be a "price to pay" for this. Because this book is about facts, history and archaeology, the author avoids most scholarly discussions and often does not present the various debates and interpretations. She just mentions that this or that issue happens to be controversial. So, in the case of the battle of Mount Graupius, for instance, do not expect this book to contain a lengthy presentation of all the theories about the location of Agricola's main and major victory: you will not find this. A related effect is that the contents, which I happened to find fascinating, may "feel" somewhat "dull" for those who might not be "Roman buffs". Do not, for instance, expect to be "entertained" in a Tom Holland style, although, now and again, some of Pat Southern's comments and dry humour might make you smile.
Then there are a number of little "glitches". One is a (limited) number of repetitions, because the same issue may pop up in different periods of Roman Britain and it gets repeated. This should however not be exaggerated. There are relatively few such repetitions and when they do occur, the author keeps them to a minimum - a couple of sentences to make the reader aware that a given topic was also an issue in the period under review. A second type of "glitch" results from the fact that the book is an overview. They are mostly simplifications and details which arise as the author attempts to cut a long story short while still preserving the core of it. For instance, Stilicho is presented as "by birth a Vandal". It seems that he was only half-Vandal. A slightly different case is illustrated by the following sentence: "the situation changed in 409, when Arcadius, Emperor of Constantinople, died." Contrary to what this sentence might suggest, Arcadius had died in May 408.
Despite this, I found that the book was a rather good starting point for someone (such as a general reader or perhaps an undergraduate student) interested in Roman Britain. It is also a rather good overview, regardless of how much one may know (of believe to know) on the topic. Four solid stars.