First off: the brush is useless. Dispose of it. Spit on it and burn it.
The texture of these pan concealers is very slick and oily. In addition to this, they're very sheer. When I used the yellow/light-flesh tone mixed together in an attempt to conceal my dark under eye circles, I patted it on with my ring finger and blended it down. Due to its thin, oily consistency, it blends easily (though if you blend too much, it sheers out to the point of disappearing).
However, it only took a couple of minutes for the concealer to settle into the fine lines under my eyes. I patted them out and the product seemed to chill out, but it was really too much fuss.