He's good but it's still mostly the same dungeon. He just ties so many NPCs into a series of overarching themes which tie into Waterdeep itself.
For example, everlasting night was created over waterdeep by something in this dungeon. It's going to slowly kill the city due to crop failure and such, unless we can find the Villain and artifact they are using, and destroy it or at least turn it off.
To achieve this, the mage's guild in Waterdeep is working with us, gave us some sending stones to communicate once a day, working with a temple to give us one divination a day.
We're slowly gathering information on what level this artifact might be located on, and one clue led us to part of that information is with some vampires on another level. We needed to find them, but eventually found their enemies, who led us to them in exchange for taking care of a minor problem of theirs.
And this is how the whole dungeon had gone. We're not just randomly exploring, but each level is tied to a larger mission of some sort. We have allies on some levels, enemies on others.
Xanathar will be trouble because we killed his goldfish in Waterdeep.
We set some mechanical beings free in Waterdeep and now they've taken over a level down here somewhere and the local residents are in a battle with them.
We accidentally set fire to a druid's trees on another level while chasing other baddies, and now she despises us though she has information we need for another quest and we need to find a way to persuade her to not want to kill us every time she spots us. Everything has more structure and meaning because our DM spent time tweaking things.
We're also trying to turn the miniature castle into a bastion with a teleportation circle to our other bastion, a bar, we own and renovated in Waterdeep.