Why you can play this game more than 100 hours? Cuz it have more than 100+ side quests with different plots, there are a great deals of weapons and armors with cool look. Exploring is interesting sometimes you can't stop exploring and get on quest, you just need to see every corner of game and open every barrel or sack in caves. Game engine is powerful, loadings are fast.
There is lot of talking about which game is better Skyrim or Oblivion. Personal:. Skyrim is great game but Oblivion is better ;)
I don't know what to say except BUY IT, support Bethesda Softworks and 2K Games. 10/10