I find the term "shared world shooter" to be very gimmicky. It's as if bungie is attempting to rebrand a genre, sort of how Apple rebranded the mp3 player as an iPod. Just call it what it is: am action role-playing- game. You can create your own character with unique skills and armor, and that character levels up as you play. You can find use magic and upgrade your weapons. These are all the classic characteristics of an RPG. If Destiny is a "shared world shooter", then WoW is a shared world hack and slash, elder scrolls online is a shared world swordfighter.
ehh they can call it whatever they want its marketing , we have seen a few co-operative shooters but not many with PVE that isn't highly instanced , so i think they just trying to emphasize we have good open world content buy the game......