Honey, sugar, molasses, and brown sugar are hygroscopic, meaning they attract and hold on to water molecules from their environment. You can see effects of hygroscopic ingredients when you leave a piece of hard candy on the counter overnight; in the morning it will be sticky because it has absorbed water from the air.
When you add a hygroscopic ingredient to a batter or a dough, it will immediately start to attract water molecules.
Honey, like all hygroscopic ingredients must be used in the correct ratio to flour and fat.
Honey is much more hydroscopic than sugar. The general rule is 1 cup of sugar = 1/2 cup of honey.
Too little of a hygroscopic ingredient, and you won't get good browning; texture will be crumbly; and product will be dry.
Too much of a hygroscopic ingredient will cause a baked batter to sink, cookies too spread; browning.will be rapid and deep.
When using honey in place of sugar or substituting part of the sugar with honey you have to consider the technique. For example, if you are making a cake using the creaming method, you wont be able to aerate the batter by beating butter and honey. You would need to use a two step recipe, rather than a creaming method.
Each ingredient in a recipe plays a specific role. If you understand the chemistry sugar plays in baking, you'll be able to successfully substitute other sweetness.