I don't keep playing on the same file, I did multiple playthroughs. The obvious reason for that is all the choices you can make, but mostly it's because I absolutely love the atmosphere, characters, music, quests, everything about this game. Just like how I can watch my favorite shows again and again, I love replaying through the story, and being able to do things a little different each time gives each playthrough its flavor. But if you're looking mostly for a playground with hordes of baddies and phat loot, this isn't the game for it.
'If you want a picture of the future, imagine a boot stamping on a human face, for ever.'