I haven't read that one. I presume you recommend it?
Madly, insanely, passionately. I cannot recommend it highly enough.
Great story, terrific, unforgettable (and entirely internally logical) magic system, superb female characters (and very good male ones, too), wonderful world building (a sort of dystopian medieval world destroyed after centuries of war alongside an early twentieth century parallel universe England around the time of the First World War and early to mid 1920s - think Lord Peter Wimsey, and public school stuff, with a touch of the world of Downton Abbey - all beautifully evoked) and incredibly, deeply, dark at times, interspersed with some very, very funny moments.
The magical creatures are fantastic, too.
Garth Nix is the author - and a very decent individual, too; he responds to tweets, and - when I spotted a typo - or contradiction (the colour of a key character's hair was described differently in two books) he was genuinely delighted and grateful (rather than surly and defensive), when I pointed this out (very politely) on Twitter.
A gentleman.
His most recent book is hilarious - "Frogkisser" - a romp through fairy stories and the work of a man both thoroughly on top of his craft and hugely enjoying himself. And - again - populated with terrific female characters who are recognisably, hilariously, human.