I rather liked Declare. As a fan of both Tim Powers' earlier work and of John Le Carré (though I haven't read either for years), I was impressed both by the audacity of the one trying to write like the other, with added djinn (rather than gin) and by the fact that he pretty much succeeded in pulling it off. It added local colour that I read the passages set around the Soviet/Turkish frontier while myself on a business visit to a former Soviet state which unexpectedly turned out to include a reception at the residence of one of the Western ambassadors posted there. He captures the tone of the disheartened and disreputable spy thriller awfully well, with the added awful secret that is not merely national security but too dreadful to be told or even fully described ("Lovecraft meets spycraft", though that tagline gives the incorrect impression that the style is particularly Lovecraftian). I should add, however, that I think Le Carré tends to do slightly better by his women characters than Powers has managed here. Not a quick read, but I enjoyed it.