I loved Oblivion (well, except for the A-Bomb), but the attention to detail and the random AI in Skyrim just blows past OB like it was "soooo, last century". Skyrim feels alive to me in a way that OB only hinted at. In fact, there's so much of it, I was hesitant to add to the thread because the things I could mention would take me all night to list. Alas, the temptation is just too great ...

* I think my first "Wow!" moment in the open world (i.e., past the beginning tutorial), besides the overall beauty of the environment, was first seeing a butterfly, getting closer as it was so lifelike, and accidentally realizing I could catch it. Shortly thereafter I found an active beehive and, thanks to the butterly, quickly found I could catch bees too -- Yehaaa!
* The first time I travelled to Whiterun from Riverwood, I came across two imperials standing next to their dead prisoner and the, now dead, mudcrab that'd killed him -- guess they shouldn't have stopped to rest that close to the river shore. Incidentally, that's also when my first gripe surfaced: What, no more crab meat? Wth!
* Seeing other wildlife interact with one another (e.g., prey vs. predator) is amazing. My favorite is seeing a fox chase a rabbit.
* Random npcs interacting with one another. The first time I saw a Fire mage in the wild, he was doing battle with an Ice mage ... nice. Yesterday I was travelling from Rorikstead to Whiterun and encountered a random farmer taking his cow as a sacrifice to the local giants camp. I sooooooo wanted to follow him but, alas, I was overburdened with loot and low on potions and had to hurry to Whiterun as it was. Compared to the lonliness outside of town in OB, Skyrim almost always involves these kinds of encounters, if not several, when walking between locations. After 400 hrs. of playtime, I still see new, random stuff (such as with the sacrificial cow).
* The detail added to some of these random encounters is a bonus to boot. E.g., I recently approached two farmers (Helgen refugees I learned) on the road only to see a sabre tooth leap out of the bushes and attack the woman, My companions and I (Eola and Meeko) ran up and killed the beasty right quick, only to hear the woman say, "Thanks for the help" as they hurried off down the road.
* I've really begun to appreciate that all the dungeon environments were handcrafted this time around. I'm a sneak, so it's really fascinating sometimes to see how they created the layout in certain spots. Sometimes, e.g., it seems they went out of their way to make it a dream situation for a sneaky type, and others almost the exact opposite.
Anyway, bugs and glitches all, the little and strange things are huge as far as how glad I am to have skyrim to play around in.
