Amazingly... large...
I think the quest lines had me moving way too far across the map too much. So either I spent hours and hours running across the map to get somewhere, or I got bored of that and started just using fast travel making the world too small and all I did was jump from place to place. There has to be a happy medium there somewhere. And of course running around, you pick up more and more quests, which means I lose track of the storyline and soon end up just quest grinding and not paying attention. While I don't condone quest hubs and just moving from hub to hub as that leads to quest grinding as well, but again with the world size, there has to be a happy medium somewhere. Such as a quest hub that from time to time sends you on an epic journey across the map where you have to fight your way there and back. But once back, gave you a break and had you perform quests in the same area again, or moved you to the next hub.
But, all in all, it's still an amazing game to play and I would highly recommend it to everyone.