Varied, hand-crafted dungeons, THE most profound change which conveniently gets ignored by the haters.

Not so much new things as things returned from previous games:

-Couriers delivering letters. This was in Daggerfall too and I really like it.
-Seperate models for different sizes soul gems. This was abandoned in Oblivion and Im happy for its return.
-Seperate models for different potions. Same as above.
-A diversity in non hostile creatures. This was in Morrowind and Im happy that not everything in the woods goes for my throat.
Oblivion only had deer.

New things:
-The night sky. Stunning, beautiful, gorgeous. The moons now each have their own orbit. The aurora. its beautiful.
-Spell tomes. I especially like that you can find one in loot.
-Disenchanting. I really like the idea of destroying an item to learn its enchantment.

Oh yeah, disenchanting.. That′s awesome Personally I feel that the entire enchanting system has been improved greatly.

1- shouts, it's funny to learn new words and shouts and use them on monsters and NPCs
2- dragons, ancient dragons on master level are awesome fights
3- perk system, allows you to create the character you really wanto to play

The fresh features i love are the many NPCs and events you encounter in the wilderness.

Fake soldiers, escorted nobles on horse, farmers who are joining the war, bounty hunters, Thalmors, vulgar bandits, soldiers or rebels with prisoners, villagers leading cows, corpses of peoples frozen to death, etc ...

A really, really strong improvement from OB.

Every thing the RS system provides. it on a whole is new, and kinda the only thing new gameplay wise and worthwhile going on imo, even if I feel they didn't tap it as much as they could.

zombieraising's pretty interesting
at least the corpse-mechanic. zombiespells themselves aren't new, of course