All of the six lost cities described in this book (except perhaps xin shalast, already covered in previous books) could have been the object of an entire adventure path. The sun temple colony is one of my favorite, and tumen brings us some additionnal lore on the 4 pharaohs of ascension. I also liked the ingenious work done on existing monster with new twists (fire shoggoth, plague bearing aurochs...) and the crystal creature template.
For each city, the "campaign" part is really useful, describing the challenge awaiting adventurers at low, medium and high level. This part also bring us some answers to a critical question, in my opinion : why would the PCs go to a lost city, which is most of the time in the middle of nowhere...
All in all, this book is useful, and brings a lot of ideas for every campaign. Congratulations to all the authors.
