The primary advantage of the square system is that it creates a grid-like pattern, which makes it easier to arrange elements in a balanced and organized way. This can be particularly useful when designing layouts with multiple elements like images and text. However, the main disadvantage of the square system is that it can be inflexible, as it doesn't allow for much variation in the placement and sizing of elements. This can make it difficult to create dynamic and engaging designs, as the layout can appear rigid and unvaried.