Somebody put some serious time into this quest. It is an involved quest, worthy of expansion pack. The aesthetics of the caverns are fantastic. And the astral plane is once again done well. No real complaints.
Of course, I'm the kind of masochist who really enjoys quests like these. For example, I managed to bug this quest on my first attempt by reaching Avatar of Araumycos's Sanctum before finding Zug's Bridesmaids and severing Zug's Connections. Paling should be added to the rear of the skull for people who enjoy jumping a lot. (I also managed to get stuck in the wrist joint on the "right" hand. I'm not sure that merits comment.)
As for the Zug fight, on Legendary the difficulty might be increased to a level worthy of her reputation.