I have Oblivion as well as SI/KOTN, but it's just one of those games I can't seem to get into. I guess I just prefer to have some direction in a game rather than just "Here's a random generic copy/paste fantasy world, go do whatever you want~"
I still plan on picking it up again, since I haven't played it that much and I haven't even touched the expansions, but I have a few other games I want to beat first.
I had lost interest in it, too one time! But I started discovering more features of the game and joining more factions. I't wasn't that long 'till it became one of my favourites.
I am currently on an SI quest which was set by the King of madness, Sheogorath. But I have to travel an awfully long way to reach my destination.