Multicam is a very effective pattern. More than just color, it incorporates a lot of the effects found in nature in mammal and bird patterns. Most conventional military camouflage breaks up outlines on a generally two dimensional plane. Multicam, while applied on a 2D cloth surface, like any other pattern, is designed to incorporate the appearance of depth as well.
Because of the backing shades under the pattern, it will reflect, to a certain degree the colors and shadows of the surrounding environment, appearing "greener" in a vegetated environ, "browner" in a desert background, and "grayer" in a winter or urban setting...