Well worth the cost, especially if you like Shamans. Lots of great ideas here also for people who aren't playing the Spirit World setting, such as anyone who has Shamanic bad guys or NPCs (which, if you aren't, you ought to give it a try.) It also includes a unique and fascinating heritage, the Spirit Eater Abomination, which is an insect with some incredible roleplaying potential. Also the new backlash table for greater spirits is going to be useful in a lot of different contexts-- basically any time the gods are angry or magic is messed up. The bottom line: high quality, broad applicability. Snap it up!
[5 of 5 Stars!]