Have just finished the lore part of the COS
Well, let's say I'm a bit disappointed about the book
I won't give it a 'meh' level, but it's only 'ok'
Quite much content is what we already known and repeated from firestorm campaign book or former short stories/ novels.
There is indeed some new stuff but quite limited to several specific factions such as anvilgard and order serpentis
Nothing new about dipossessed, wanderers or shadowbalde etc. They just rectoned shadow warriors to make them shadowblade and pretend swifthawk agents never exist (strangely eldrich concil does get mentioned). Although flaggnent is in the book but no lore for Devoted of Sigmar—— kind of making sense because without witch hunter and warrior priests or even excelsior priest, flaggnent is the only Devoted unit, who would bother explaining what they are?
The eventline in the book is which I believe to be the shortest one in 2.0 battletomes.
I also believe there is only one (living city battle scene) or two (if you count cover) new art in the book, the rest are just copied from WHFB and Firestorm.
Some funny contradictions also occured, such as saying 'Sigmar punished and killed all those people with malice and cruelty to purge taint in his realm' and later describing how dark aelves, aka Sigmar's close ally in Azry, are cruel and merciless.
Seraphon got mentioned in first several pages as allys of Free Cities but rulewise COS can't ally with Seraphon.
This book indeed helps to flesh out the setting a bit, however far less than I expected . For Sigmar's sake I still don't know how a day of normal man should be like in Hammerhal, it's claimed to be a continent-sized magical metorpolis with population over billions but only gives me a feeling that it is some random fantasy medieval city with elements of magic and steam punk.
Overall I am not satified with this book, it is still worth reading, but not good enough to change the hollowness of the contemporary setting.
BTW: JR's 7 short sotries are still gold and obviously my favourite part of the book, which actually flesh out how different races fight together, I especially like the one of Greywater Fastness with stubborn Dwarf Cogsmith.