We went into the Darkening Depths with barely a torch to light the way; unsure of what we would encounter and a list of quests to complete. About an hour later, the council of goblins lie at our feet and the Darkening Depths was vanquished.
This dungeon was much longer and drawn out than the Realm of the Fae, but if you are simply doing a boss run, you’ll only have to do the lower portion. That cuts off about 15 minutes of time or so. The bosses in DD are much more strategy oriented however. Watch out for pools of bad (fire or whatnot) and setup a kill order before you jump into the bosses… oh, and listen to the NPCs when they tell you to “Get him out of the moonlight!”