Soldiers of Fortune is the best damn sourcebook out there. Even if you're not a 4e consumer, you will find a ton of great new content within the book. As an added boon, fans of the Midgard Campaign setting (Kobold Quarterly) will find some truly juicy bits of lore within its pages. Also, I detailed a greater deity (Thor!) that I am fairly sure no party could take (yes, that is a challenge).