It's a common way to describe someone who is:
* Attractive in a classic, idealized way: This simile often suggests a kind of timeless beauty, like the beauty found in traditional paintings.
* Harmonious and well-proportioned: The image of a picture evokes a sense of balance and perfection.
* Pleasant to look at: Just as a picture can be captivating, the person being described is someone who is enjoyable to gaze upon.
However, the simile can sometimes be considered clichéd or overly simple. It may not be as nuanced as other descriptions of beauty, and it doesn't necessarily capture the unique aspects of a person's appearance.