I liked the swamp , and I didn't think it hard to navigate at all. Obstacles in the center, everything else more or less had a clear path. The final swamp, well I felt pretty swamped out by then so I didn't do anything but the main quest.
I disliked the sewers and dungeons, rather than have 3 feet of visibility I would crank the brightness and gamma all the way up, instantly making everything very ugly.