This is a good presentation and introduction to Roman legionaries from BC 298, the reorganization of the Roman army in manipules and the beginning of the third and last war against the Samnites to the rise of Marius and the eve of his own military reforms on 105 BC.
This little Osprey volume displays the usual structure that can be found in the series, with introduction and chronology, origins of the manipular legion, recruitment, training and organization, followed by a piece on appearance and equipment. The book ends with a section on the legionary during campaigns and another one on his "experience of battle".
By and large, and for those that already know quite a bit on this period, there is little new or original. Even these, however, will find value in this book because it clearly illustrates the hybrid and transition Roman army and its shift from a hoplite type organization to what would become the "classic" Roman legions by the time of Marius. For those who are new to the subject, however, and those who are looking for some rather vivid visual illustrations, this book will be fine for you.
Both the contents and the eight plates are, however, well presented and thought out. The plates in particular are distributed throughout the book to cover evenly most of the sections: recruitment, training, one for equipment of first and third line infantry, and one for cavalry and then one each for battles on land, on sea and for siege. A minor gripe here is that there is - oddly - no plate for the Principes - the second line of legionaries. A minor positive is that the plates allow the reader to get a clear grasp of Roman equipment, and Roman helmets in particular, of the time.
A final merit of this book is to explain the advantages that the manipular formation allowed the Romans to build over their various foes, whether the Carthaginians, which initially were using a hoplite type organization, the Gauls, or the Hellenistic monarchs and their pike phalanxes which was itself an evolution from the hoplite phalanx. A related feature is to show through the equipment section how versatile the Romans were and would remain for centuries in adopting pieces of equipment (with the gladius being one of the most well-known examples) from their foes and improving on them.
Two final remarks need to be made, however. One is that the book does contain a number of repetitions which may be mildly annoying for some. Another element is that the text is very largely inspired from Keppie's "The Making of the Roman Army: From Republic to Empire" to the extent that, at times, it almost reads like a shortened version.