It's interesting how opinions differ on these games, I think it just boils down to individual preferences. I personally don't get how anyone could think the dungeons were so much better in Oblivion. Bigger yes, better no. Part of a good dungeon, imo, is the reward for exploring it, and that's where Oblivion failed miserably. Few of the dungeons in Oblivion contained anything worthwhile. As Relayer pointed out, there was really no point in exploring them.