Awesome resource. The World of Kos, and the remainder of the work the Skirmisher guys have done to flesh out the Kos setting, is fantastic.
This particular item approaches the setting from a fairly top-down perspective, outlining the world at large, as well as the creatures and organizations that inhabit in, and a surprsingly thorough section on faith and worship.
It features the impressive and compelling work of a number of artists to help pull you into the Kos setting, as well as a number of highly detailed maps for use in a wide variety of RPG systems.
Most importantly, I love how well laid-out everything is. As a relateively newer player, it was a breath of fresh air to read things broken down into easy-to-understand, yet considerably detailed sections.
Overall, I think World of Kos is an awesome supplment for any fantasy or RPG setting, and Skirmisher has done an incredible job at creating a world that is able to slot into a wide range of systems without any major issues.
Keep up the good work guys!