Pathfinder Player Companion: People of the Stars.
The Basics: Distant Worlds is a full-color 63 page Pathfinder setting book. The retail price is 19.99. There are three chapters. The first is a gazetteer of the Pathfinder universe. Each heavenly body gets about four pages which is an overview, a section on adventuring, important locations, and adventure hooks. The second chapter (which is only four pages). One page of this is a title page, two and a half are pretty bare bones rules and discussion on getting between planets and dealing with other atmospheres, and finally a half page with two spells (planetary adaptation, and mass planetary adaptation) and one magic item (pressure suit). The final chapters gives us six new monsters and a page listing monsters from other books and what planets they tend to inhabit.
The Good: The descriptions of the planets give you a good overview. Each world feels pretty unique (yet archetypal to sci-fi fans). The new monsters are all unique, yet familiar. The Shobad are my favorites, but who doesn't love four-armed tribal warriors?
The Bad: There's just not enough material in this book. I was really disappointed in the lack of discussion of vessels and how to get in between worlds (this is because I'm a Spelljammer fan). Also, the book has tech. If you don't like tech mixing with your fantasy, stay away.
Final Thoughts: With the amount of information that could be in this book, I think it would have made a great hardcover. I also feel like this book and People of the Stars are a part of an incomplete collection. I feel like there needs to be a third book that discusses space adventuring. I don't recomend this one, unless you really just want to read about the other planets. People of the Stars is cool, especially if you're running Iron Gods, but Distant Worlds is a super niche book.