My personal opinion on desert digital is that it works 'best' in the desert. But then again I don't think camouflage matters much. Bob, wearing green, can preform just as good as Joe, wearing tan, in the desert. I don't actually have a digital uniform, but those I do seeing wearing it (Compared to others wearing different desert camo patterns) seem to camouflage slightly better into the terrain.
I prefer multicam though.