First nearly nothing felt unique in Oblivion. The Creatures dungeons and locations all felt computer generated and generally they were.
Second the landscape was lame just green hills with trees it was too open. I don't know how to describe it but it was too easy to go straightforward to every spot you want. There were no natural barriers that force you to skirt around and therefore exploring never felt like "wow I've never been here" but like "hey I walked half an hour but everything looks the same and I saw this spot from my starting point anyway". I never felt like an adventure it always felt the same Cyrodill was just too plain.
Third it often lacked the right flair it was a bit too bright and clean and the NPC's felt not very individual in their habit.
With all this Oblivion never felt very unique compared to Morrowind or my favorite RPG Gothic (the old series). There you walked through a valley and encountered a broken cart plundered by bandits the owner nailed with arrows to a tree some loot laying around left by the marauders. You couldn't walk straight ahead because there were lots of plateaus and so everything felt bigger.
Or you entered a cave near some orcish camp and found a diary of someone who described his last days surrounded by orcs. That's what I call an adventure. And when you come to town behind a house you see the smith working on his anvil telling you he's busy at he moment some others are talking in a very vulgar voice about the situation an so on.
Some of this seems to be fixed by Bethesda. I really liked the scene with the windmill and the men chopping wood or so it really looked alive. Also the few insights into the game gave me a good feeling about the landscape it looked more handcrafted and interesting to explore.
I hope you understand what I mean. I bet there will be some replies like " then go play Gothic" or the like but I really liked Oblivion the gameplay was the best I've ever had in a RPG. Now I wanna know how you feel about this issues.