When used properly in this manner, the performance is top notch. A brush can work, but you are not trying to whip up a typical lather, just simply trying to add moisture to the cream, and a brush will not allow you to feel when the proper consistency and moisture content has been reached. Then, after wetting fingertips, you work the cream on your face to the right consistency and slickness. They work best by applying a small amount all over the face with fingers. The reason is that these creams are not intended to be lathered in a bowl. Try to whip up a good foam and the lather collapses. You apply a bit too much or too dry and they clog your razor or don't let the blade do its job. There are quite a number of creams that fall into this category.
