According to official information, the most important aspect of this new dungeon is that it holds hidden one amazingly powerful artifact. Blizzard explains:
“Within Deepholm, the domain of the earth elementals, the malefic Dragon Aspect Deathwing is on the verge of executing a catastrophic act: to burst forth from the Elemental Plane into Azeroth. Doing so will ravage the surface of the world and breach the barrier that separates Azeroth from the elementals’ realm. Whether Neptulon and his subjects have entered into an alliance with Deathwing remains unknown. Regardless, if Deathwing’s actions create an opening into the Abyssal Maw, nefarious and honorable factions alike will seek out the fabled weapon carried by Neptulon. Whoever secures the artifact will have control over the world’s seas, a power that perhaps no one, not even members of the Horde or the Alliance, should possess.”
Personally, even though impressed by this trip to the “underwaters”, I’m not really impressed with the new art. Maybe a bit more could’ve been done, don’t you think?