I bought this book because I am running a Dark Tapestry/Osirion campaign and thought I would get enough useful out of the Tumen section to make it worth it. I did not. I got almost nothing usable from that, and most of what was usable is available freely online, in the d20PFSRD or on Archives Of Nethys.
I also read through the other four cities described, and I wouldn’t say they’re any more useful. Some are much worse; Ilvarandin includes two near-epic factions gearing up for a war, where the defender builds a wall along their south side and leaves the north open protected by a river. Rivers, notably, do not block things that can fly or levitate, which, at the power level they’re operating at, is basically everything. They also do not block line of effect for spellcasting, which, again, most of their foes are capable of.
Every city described is given three “using this in your campaign” chunks: One for low levels (1-7), one for middle levels (8-14), and one for high levels (15+). It’s clear that making this possible was a priority well above making the cities make sense or feel like they had real personalities animating them. This resulted in them being mediocre-to-bad for any level instead of really good for one chunk of levels and mostly useless to the others.
Result: I got more useful adventure seeds out of skimming the free Wayfinder (fan-made, Paizo-distributed) magazine, and the crunch, such as it is, is all available online.
Substance: 3/5 (but all available online so effectively 1/5)