There's a main questline, which takes 1 day, then there's about 200 side quests, a Fighter's Guild questline, Mage's Guild questline, a Thieve's Guild Questline, and a Dark Brotherhood Questline, (that's where you murder people stealthily and in quiet locations where noone else can see you.) Then, you go to a bunch of shrines and there are quests for you there. There are also a LOT of monsters to fight.