Aside from lore implications that threaten to destroy the world, players will also have access to two new dungeons, two new zones, and all of the new items, weapons, and armor that you could ask for. So take wing in the game and start fighting as if your continued existence depended upon it, seeing as how it sort of might.
Aion is now live, allowing players to climb to level 75 and become powerful Archdaevas. Which is a good thing, because Echoes of Eternity is about the biggest possible scuffle for all of the marbles. The Aetheric Field established by Siel is shrinking, and the artifact that could save Atriea might well spell doom for either the Elyos or the Asmodae. Whoever retrieves the artifact from the Tower of Eternity is going to have quite the decision.
Source: NCsoft press release