I own one of these, and they're the exact tool for the job when you don't have, or would rather not use a light stand to mount a light source.
As a rule, the BIGGER the light source you can light a subject with, the more flattering the image will be.
Swivel that flash to 3 o'clock or 6 o'clock positions to find walls to bounce light onto your subject, rather than hitting them squarely with the flash head, which effectively is a much smaller light source than a wall. An alternative is to point the light straight up at a ceiling, which if low enough will be better than the...