Just played half of the adventure from this book tonight.
The first half of the book is setting information on the Terris Dominance in the days of the Final Empire. Geography, culture, some scraps of history, most importantly how Terris actually works under the Empire, how the Breeding Program is managed by the Steel Ministry, and how the Synod manages to preserve Terris heritage in spite of it. Even if you never set foot in the Terris mountains, this will hugely inform the roleplay for a Terrisman character, as it's a background they all share. Covers many topics only hinted at in the books, but in a way that is credible and consistent with the lore.
The second half of the book is the adventure "Justice, like Ash". This is a very fleshed-out adventure worth 8-10 hours of play at least. Scripted in detail with many different options, very well-written dialogues that add texture to the characters, and a dramatic moral dilemma as the climax. I'm running this as an intro to the game, and although it's less typical I think it's more self-sufficient than the primer adventure.
The only thing keeping it from a five-star is the adventure contains some glaring errors in fact - contradicting elements from earlier in the book, or from the source material. Nothing huge but it might trip you as a storyteller, or cause cognitive dissonance for those who know the source material.
- Terris women in Luthadel, that's not supposed to happen.
- Reference to Terrismen born outside Terris, that's also not allowed.
- Travel times between cities misrepresented - looks like the author assumed they had steam boats instead of slow human-tugged boat.
Only the last one is a real problem for the adventure but nothing a good DM can't work around.