Trees, trees, and more trees. Big super-intelligent trees with godlike powers within the Shadow... except against things like Shadows of the Serpent with grudges against Morgan and the Outsider-based technology of the Kanawa Corporation.
Endor is also home to the Ewoks, cute little furry primitives who hardly ever eat outsiders for dinner these days. The Ewoks are remarkably good at fighting high-tech people using their limited technology; when organized into a single force and led by Sumire, they quite easily captured the Kanawa Corporation logging base after its reality bubble was destroyed.
Endor has been confirmed to be the hiding place of Ksinge Ivan the Terrible's tomb (actually, a prison for an undead Soulstealing Ivan) which also held Withywindle, Sword of Wood. Ivan is now destroyed, and Withywindle is in Moriya's hands.