Here are some of the things said in reviews of the first (1993) edition of Roman Military Equipment from the Punic Wars to the Fall of Rome:

Its approach pays off: broader issues arise from the study of the material… Antiquity

The strength of this book lies not just in the information provided by its text and illustrations, but in its end-notes and bibliography. The Classical Review

Without such a study, discussing equipment in a regional fashion would be far more difficult, and RME should provide a useful impetus for other researchers. This will be a popular book… Journal of Roman Archaeology

Over-ambitious perhaps, but encyclopaedic in its coverage and impressive in the depth of its learning, it will nevertheless become an indispensible reference for all students of the Roman army. Britannia

This book will be a major reference work, and a solid foundation for future research for a long time to come. Archaeologia Aeliana

The second (2006) edition of Roman Military Equipment from the Punic Wars to the Fall of Rome has also attracted some favourable comments:

This was a ‘must read’ from the moment it was published … the 2006 second edition was even better. Ancient Warfare Magazine

This is a serious academic study of interest to archaeologist and historian, fully referenced, based on considerable scholarship and with an enviable reputation. Amazon UK

Sehr gutes Buch! Habe noch nie zuvor derart detailiert und strukturiert über die militärische Ausrüstung der römischen Armee geslesen! Amazon Germany

It is, quite simply, the bible for Roman military gear. Simon  Turney

The Spanish edition sems to have been well received too:

Hablar del ‘Bishop y Coulston’ es la forma abreviada de referirse al mejor manual moderno, y casi único desde 1926, sobre el tema. […] este es un libro necesario para un historiador de Roma y de cabecera para cualquier aficionado a la Historia militar. La Aventura de la Historia

Su mérito reside en la exposición clara y amena, así como en el rigor de los datos, documentados no solo con los hallazgos más representativos, sino también con los descubrimientos más actuales. Desperta Ferro Antigua y Medieval