Very fun! Several strong points, a few constructive criticisms for future releases.
Overall it's an imaginative take on a small barony in Baltimore. There's some interesting setting ideas that need to be further fleshed out, but then, it's only a 15 page book for a reasonable introductory price, so that's is not an issue. The author has clearly done his research and has some well defined ideas on this setting. And the setting itself is well chosen, with great potential for further exploration.
The adventure is a wonderful little exploration, excellent for setting up a chronicle in the region. It is definitely worth the price for the intro adventure into this setting, and I hope the remainder of the series is as well produced. The detail on the primary encounters is excellent, there's a great little mystery, and a few twists that are definitely fitting in mood and theme.
The primary quibble I have with it is overuse of artwork. Odd, yes, considering the nature of C20. But for a 15 page supplement there's only about 10 pages of text - several pages are artwork taken from other official changeling works. That's fine for mood, but when 3/4s of a page is taken up with pictures I've already seen, it seems to me to a wasted opportunity.
More detail on the setting, which I do want to see more of, could have been introduced here instead. Some things that would have been useful, especially for novice Storytellers, would have been even a brief description of the Baron's Freehold where the adventure starts, including some suggested plot hooks on how to introduce the mystery. And perhaps even a hand out on the written aspect of the mystery in the adventure, which is described, but not explicitly shown.
I'm also keen to learn more of the nature of the Thallain infiltration of the city, which is mentioned but not examined.
Overall a solid introductory work, and a great way to start your story in the Barony of Flamingos!