I should probably have mentioned that I haven't read any of his books either, so have nothing to say about their merits as fiction (my parents tell me they're crap, but entertaining crap). When it comes to the subject of historical accuracy, those of us who aren't historians don't really have any choice but to rely on the word of the many differing voices who claim expert status. But some of the nonsense about cryptanalysis in Digital Fortress is just painful reading even to know-nothings like me, so I'd definitely take the word of those historians who disagree with Dan Brown over that of Dan Brown.