There is something about portraits that taps into our most ancient instincts. We evolved to recognize human faces: it was a basic survival skill. So when we see a painting that can create that same spurt of recognition as the face itself, it amazes us. It's something that can't be suppressed, the same instinct that makes us abhor spiders or snakes and take notice of bright colors.
That's one of the reasons I've always loved making portraits: I love to see the instinctual response of the people who see the portrait. I also get a kick out of taking photos of my portraits and having the camera box in the face, because it recognizes it as a face. I love portraiture it because I enjoy expending all my energies on creating something that is true to life, and portraiture is a genre that rewards that effort.
Above is a portrait I did yesterday.