Only protects yourself and not the surrounding group. So when you use this positively delightful +6 versus all spells, you are the only turned into a god against magic. :(
It´s actually +8 versus all spells so it's even worse that it only applies to you! It only affects party members unfortunately, much like Mass Camouflage. Because PFS should only affect X members (probably 3), it cannot be fixed using the same system we have for Aura of Protection because it will hit everyone in the surrounding area which could very likely be >3
War Cry operates under the same principal and it gives allies a +2 ab/dmg bonus.
It was just overlooked when the DMs were updating our spells.