They are lighter than whole wheat hence they make lighter cakes, pastries and cookies than whole wheat which make the end result more dense. (chefinyou.com)
Because of the density of the cake, this was very easy and there was no collapsing or crumbling that you might find with lighter cakes. (cakepossum.com)
I wouldn't try using it in light cake or pastry recipes, however. (lawsofbliss.com)