The advantage Personology has over traditional Astrology is that it's even more personalized. Have you ever had the same astrological symbol as someone else, both read the same forecast, and had a totally different day? Or maybe your personalities simply don't match. Personology helps explain those differences, so even if two people happen to both be a Pisces, they'll have different birth charts.
Just in case you're in here accidentally, Personology the astrology is different from Personology the art of reading people based on their clothes, body language etc.