One of these missions is hated. The other, is loved. Let's discuss why. Both are said to be confusing to navigate, Thieves' Guild by the players, and The Sword by Garrett himself.
Personally I never found The Sword difficult to navigate in, because it follows the rules of good mapping, where each area is distinct from others, through use of unique textures and sounds. In contrast to that, Thieves' Guild had a lot of sections which used the same textures over and over again and seemed to go on forever. It was easy to get turned around and not even know it until you are staring at the same area you were just looking for a way out of! Note that I rarely use maps in games, and mostly go by learning landmarks and architecture instead.