As historical fiction goes, more emphasis is placed on the history here, a compelling enough story on its own without some of the padded writing that can afflict a lot of the genre. Yes, the prose is workmanlike, but Druon is foremost an historian interested in painting the background of France c. 1314 at the same time as he's delineating the important figures and their motivations. The Iron King himself, Philip The Fair, becomes increasingly interesting as the novel nears the end.
Heh, just realized I'm typing this on Bastille Day. Vive la France!