This book, like most in the Osprey Fortification series, provides a very good overview of its topic in its relatively short breadth (64 pages, roughly half of which are illustration).
The physical characteristics of the fort are especially well covered, especially in terms of illustration (drawings, etchings, photographs and contemperoneous artwork). The emphasis of the book is on the physical fortifications in the condition they were in during the two famous sieges of 1480 1522. Little discussion regarding the fortifications is presented outside of this time frame. The book is richly illustrated with drawings and etchings showing the condition of this fort during the two sieges. As the fort is today, more or less, in the same state it was at the end of the 1522 siege there are also many excellent photos that illustrate its key defensive and architectural points.
There is also considerable discussion as to strengths and weaknesses of the fortifications along with how they developed over time (i.e., closing off of many entrances, building of large moats, building of secondary set of walls and fortifications in front of main walls and in moats, etc.). The primary emphasis, again, is on how the fortifications developed between 1480 and 1522. The illustrations show how the fort's defenses were massively expanded during this interim period. In addition, there is a good discussion, along with accompanying illustration, of what certain features were for (i.e., machicolations, tunnels that permitted entry from fort into moat floors that permitted sallies, etc.). The book also covers how responsibility for fort defense was partitioned, by lines along the wall, by nationality and a brief discussion of the Knight's of Saint John and non-military functions of the fort (to assist pilgrims to the Holy Land, etc.).
The book does have a few weaknesses which do not permit it to be granted a five star rating however. The most important of these is a lack of a combat history of the two sieges with an emphasis on how the fortifications performed relative to the strengths and weaknesses identified in the book. For a good history of the two sieges Eric Brockman's book "The Two Sieges of Rhodes, 1480-1522" is highly recommended by this reviewer. Other weaknesses include a lack of cutaway drawings, lack of photos some of the very impressive still standing interior (the Knight's main banquet hall is incredibly impressive but not covered in book) and some discussion of the geopolitical importance of the fort and why the Ottoman state expended such great efforts to invest the fort. In addition, as the fort is currently standing in more or less the state discussed in the book, the book could have added a paragraph or so on travel and tour recommendations for those interested in actually visiting the site. For the fortification aficionado with the inclination, time and money to spend a visit is well worth it (as the pictures in book taken by the author make clear).