It’s a fun concept. Players get a guaranteed random T4 thrall when they reach the top of the ruin with a 12hr cooldown. 62 different thralls in the loot table ranging from low quality fighters to sought after shieldwrights and bladesmiths, etc. There are two unique thralls that are slightly better than anything else available in the loot table also - basically relic hunters with 30% more HP.
The dungeon has some fun bosses that drop unique items. Each area has a portal to return you to the previous one if you fall. And if you die there is a shrine in the desert respawn point to return you to the dungeon.