This shows the results of on-camera flash. Note the flat lighting and harsh, distinct shadows, especially distinctive on the background. Note the highlight reflections directly in the middle of the round chess pieces. Unless you walk around with a light on top of your head like a coal miner, you don't normally see shadows like this in everyday life, so they don't look terribly natural or pleasing.
This was taken with a small, cheap Metz 20BC-6 flash on its auto setting. The best modern computerized TTL flash units will provide essentially this same light quality. They can provide much better exposure metering abilities, but this shot is well-exposed as it is. The problem with this picture isn't exposure metering, it's the quality of the light.
This was taken at f5.6 using the flash's auto setting
Here, I've used a Sunpak Auto 383 flash on a lightstand to the camera left, a bit above the subject. The flash is aimed directly at the subject, with no umbrellas, bouncing, or diffusion involved. The shadows are still stark, but simply getting the flash off-camera brings out the subject's depth better than the first shot. Also, the shadows have moved off the background.
This was taken using the flash's auto setting, at f8.
This picture was taken with the same light in exactly the same location as the previous one. The difference is that I swivelled the head around and bounced the light into a 45" umbrella. Notice the softening of the shadows, and the more gradual transition between lit areas and shadow areas. This kind of lighting wouldn't be bad for a portrait.
This was taken using the flash's auto setting at f8.
Here's a two-umbrella portrait. To light this photo, I used a small monolight fired into a 35 inch umbrella almost 90 degress off to camera left for the main light, and a Sunpak 383 on camera right fired into a 45 inch umbrella provided the fill. Exposure was f8. The lights and shadows give a 3-d look that would be absent if I had used on-camera flash.
