I think only thing that improved compared to Oblivion are the voice-actors (still quite a lack of em), character customization, music and character models. It's also visually more pleasing than Oblivion, imo.
Side-quests are still very boring, you just go to Dungeon A to kill monster B or Collect 10 pieces of item X or bring object A to person B. If you like doing errands then u will love it.
Also it is still very light in roleplaying, but heavy on loot-collecting and exploration if that's your thing in RPGs.