Before I plunge into expressing my views about these books it’s just fair to give a small summary regarding the story [for the sake of continuity to the previous post if not anything else].
So in the previous book a doorway had opened into another world [Cittagazee] and Lyra had gone through it. Will, a 12 year intrepid boy is on the run and through a window between his world and another, finds refuge in the latter. Cittagazee is full of specters, some transparent creatures visible only to adults and which suck life out of adults rendering them alive but still lifeless. So anyway, Lyra and Will become best of friends, get hold of Subtle knife, which is a very unique knife that can cut anything, even windows between different worlds. They are in search of Will’s father, in course of which they meet some witches, who are keeping them safe and helping them reach Lord Asriel. Lord Asriel meanwhile is assembling the biggest army to fight Almighty or Creator. Whatever!!