If there's one thing that's really impressed me about Skyrim, iot's the Dungeon design.
Every time I enter Ruins/Caves/Forts, I'm not really sure what to expect, both in terms of enemy composition, layout and difficulty, which I really enjoy.
Look at the verticality of
this -
up and
down.
As you can see, this is a Dwemer Ruin, for a Enchanter/Smith like me, I'm in heaven as I'm getting jewels, Dwarwen Ore and Soul Gems a-gogo.
There have instances of deathrap dungeons too - when you get in, you can't get out which I've had to change my play style to survive.
The biggest criticsm I've seen levelled is that the dungeons are linear experiences, which I suppose is valid enough but for the quantity of them in the game It's a touch harsh to pick fault with it.