Like the Mines of Moria.
The Deep Roads—cavernous, hazardous, labyrinthine, and as arduously exhaustive as a treatise in
Dwarven political history—is not the most fondly remembered area from Dragon Age: Origins. Even so, Dragon Age: Inquisition which focuses mainly on Orlais and Ferelden, mostly kept the dwarves at arm's length, leaving fans wondering what was happening in the underground Dwarven thaig of Orzammar that reduced the city to a mere blip on the Inquisition war table. Thus comes The Descent, a dungeon centered on the Deep Roads and operates like a minor D&D campaign that ultimately teases where the Dragon Age story might be heading in the future without bringing a satisfying resolution.
Unnatural earthquakes continue to ravage the lyrium mines pivotal to the Dwarven economy, and while Orzammar would prefer to keep this dire situation quiet, both the Legion of the Dead and the Shaperate have yet even to uncover the cause of these shockwaves, let alone the solution. Worse, the earthquakes have broken multiple ancient seals that barred the darkspawn from swarming toward the surface. Given that lyrium powers the Inquisition's magical forces and darkspawn threaten all of Thedas, Orzammar have called for your much-needed assistance.
If just to prove that The Descent is meant to be played near the endgame, if not after the main campaign, the mission begins with a beatdown. A few steps into the mines and you're locked in a fight against a hulking ogre, so if your combat skills are a bit rusty, you'll get a quick refresher. On top of that, the widened chasm running along the edge of the opening area introduces one of the central themes for the levels in The Descent: endless pits. Fall in one of these and your character will return to the surface with but a sliver of health left, so watch your step or you'll waste a handful of potions.
As its name suggests, The Descent has your party head steadily down into the layers of the mines as you decimate scores of darkspawn, spiders, and emissaries. Along the way, you'll escort a female Shaperate who can listen to the Stone (in much the same way that a woodland elf can listen to the forest, I imagine) and a hardy male Legion of the Dead commander. The other level-based theme of The Descent are gears, tucked away in the darkest nooks and crannies, that can unlock various doors spread throughout each layer.
For more or less a six-hour adventure, depending on how thorough you are with the collectibles, The Descent does an adequate job in terms of challenge and interesting level design for as linear as it is compared to the more freely open environments in Inquisition. You'll still discover points for landmarks, treasure, and expeditions which can be worked at the DLC-specific war table near the beginning of the side campaign and provide pathways to previously inaccessible environments. Going through each layer over again is worth the exploration.
However, there are more than several blips along the way. The campaign doesn't last long enough for you to care much about your Shaperate and the Legion of the Dead companions, and the ending feels too rushed and vague to feel resolved, as much as its ramifications are worth discussing. The ending boss is needlessly difficult for melee characters, but a cakewalk for a ranged character who can poke away from afar and dodge spikes rather easily. Actually, some of the mini-boss emissaries might be even more challenging than that since they can regenerate their shields. Even so, there isn't that many high-level equipment to gather from The Descent, so apart from extra experience points, there's little to take back from the DLC.
Though The Descent has the foundation of a strong side campaign, the characters aren't memorable enough and the story finishes too loosely to leave a lasting impression. Perhaps if it came coupled with a fully reimagined Orzammar or characters who have some permanence, it would have been an adventure that wasn't as closed off and didn't have an awkward aftertaste.