pgriz's simple, daily-life snapshot of a moment he wanted to record shows just how marked an effect Changing The Frickin' Light can make on the final result one achieves in a photo. But, even more importantly is the comment pgriz made: he saw the lighting effects from, "the early morning light," which in this case created strong sidelighting, with almost perfectly even light intensity in the highlights--because the sun is so,so far away, that the light output it creates is very even, and the only modulation of early or late sunlight is from things that block the light, like the window blinds, or three-dimensional objects, which create shadows.
So, basically, we have an experienced photographer, pgriz, whose got his camera out in some of the best light of the day--early morning sunlight, coming in at a pretty strong side-lighting angle...he is in other words, shooting during a period of "good light". The very subtle,small specular highlight that the flash created inside the coffee cup, where the coffee touches the left side inner rim of the cup, adds a BIG visual clue that the original photo lacked, because the inner part of the coffee cup is just blackness. There is also a very soft, subtle diffused highlight on the surface of the coffee in the flash-added shot. These two things, specular and diffuse highlights, are two of the KEY, CRITICAL THINGS FLASH CAN ADD to photos. Specular highlights and diffuse highlights.
He wants a bit more shadow detail, which is sensible, since the sensor tends to make the shadows look unnaturally dark compared to the way the human eye and brain can see the shadows, so he introduces some electronic flash..just a little bit...not too much...but enough to lighten up the shadowed side of the coffee mug. Tripod, slow shutter speed +small aperture for decent depth of field + ambient light exposure appropriate to the light level + flash for fill...only five basic things to make the shot work and work well. But the MAIN THING is that pgriz was shooting a scene that had good light, attractive, interesting light, to begin with. Early and late in the day are good times to shoot interesting photos. provided that you have the right tools (like a tripod, for example, or a VR or IS lens used carefully),and you use good methods, like reflector fill, or flash fill.