Fascinating setting, and I love the fungal imagery that permeates this text. The idea of two cities, one underground and full of spores, and the other atop it, with two populations in various stages of conflict and denial is fantastic. The imagery really is the strongest thing here, mutations and colour and mushrooms transforming both individual bodies and entire urban ecosystems. Not quite as strong, perhaps, is the central relationship. Or maybe that's not quite accurate... the relationship between the Shriek siblings is interesting, and it is affecting and layered, but the (fake) editorial comments at the end show an editor wondering if he'd let things run on too long, and the fake editor is right. I can't help but think (as I do so often in fantasy) that this could have been cut down substantially and not much notice taken. Had it been a hundred pages shorter at least I might have had more time for Janice and Duncan, but there's only so many times you can watch a couple of people fuck up when the setting is more interesting than they are.