HDR ("high dynamic range") helps you get great shots, even in high-contrast situations. The best parts of three quick shots, taken at different exposures (long, normal, and short), are blended together into a single photo.
Use HDR. (iSight camera) Tap HDR. The flash is temporarily turned off. For best results, keep both iPhone and the subject still.
Keep the normal photo in addition to the HDR version. Go to Settings > Photos and Camera. HDR versions of photos in your Camera Roll are marked with "HDR" in the corner.