The Grand Dark

First half 5/5. Excellent worldbuilding, atmosphere building, characters building. Perfect pace (not at all too slow). Feels like a mixture of “Grand Budapest Hotel” (without the comedy), Kafka and decaying Bioshock (the first 2). Dark, original and fascinating. Somewhat similar to Higgins' Wolfhound Century series, but just in feel (here a German universe, there a Russian one).
Second half 2/5,because it mostly wastes the great worldbuilding in just running around with half-baked, unoriginal action. It feels like the author cannot decide what storyline to go for, so he tries all of them very briefly, not really completing any. It would have been 1/5,but it is somewhat saved by a few good revelations.
So, an average of 3.5. A book I would recommend, but will not read the sequels.