I came to this novel after having seen the Ridley Scott film version; they are two different animals but each has their own attractions.
Ignatius` novel is, of course, the primary source of the plot - which I won't go into.
The narrative is well paced, slowly building up a fairly believable picture of an espionage operation in the Middle East; the portrayal of the CIA is pretty consistent with factual books I`ve read - the incompetence that exists at some levels of the organisation and the institutionalised denial that they ever make mistakes - Ferris is the main character, but it is Hani Salaam, the GID intelligence officer who is perhaps the most intriguing (literally) character in the book.
The film truncates the storyline, excises much of the secondary sub-plotting dealing with Ferris's private life and beefs up the part of Hoffman; this increases the pace but also subtly places more of an emphasis on the American side of things than I felt was apparent in the novel, which presents a much more balanced view of both Western and Middle Eastern worlds.
On the whole, the book is much more rounded and better paced for this kind of story telling; it is essentially about the methodology of espionage, the construction of untruths, the ruthlessness of creating devices to penetrate and confound the enemy's system with little regard for those civilians - like the architect Sadiki - who are used as pawns in an elaborate and deadly game; characterisation is less important and only a few of the main players are properly developed to any extent.
The film is flashily exciting visually, providing its star cast with good roles but is less engaging and more formulaic overall - still a good watch though.
This is a decent and absorbing thriller which in the main avoids following the usual clichés and makes for a very entertaining read.