The Looking Glass War is chiefly a story of hubris and futility, as (Leclerc) a head of intelligence operations desperate to stay relevant and restore his department to the glory of days past takes increasingly needless risks for the sake of his own pride. The mistakes are nearly endless; acting on clearly bad intelligence, supplied with out of date technology, using previously burnt agents, sending people on missions they're simply not trained for and are ill equipped to deal with, failing to do even the very basic due diligence. 

It loses itself in the second half as the story moves away from Leclerc and on to the training of Leiser. He's an odd duck, to say the least, and not a particularly engaging character to follow which is a shame considering so much of the book is focused on him. There's also definitely an issue with the attitude towards women in this book with the Wives and mistresses all being portrayed as reckless information leaking harpies which is a great shame. 

As is to be expected the actual writing from le Carre is great throughout but the mystery of the plot feels a little transparent so presumably it was intentional all along for the reader to see through it but unfortunately this leaves a feeling of disinterest in much of the plot as a result. Then there's the real mystery, namely that of why Control lets this whole thing play out at all which is interesting but unfortunately very much a background issue to the main plot.