At the risk of an unpopular comment, I actually do think there is something to it, but not the "your daily horoscope" bs that used to appear in newspapers. I am in the midst of reading John MIchael Greer's translation of the Picatrix and it is pretty much all based on medieval astrology. (You'll note that JMG is no intellectual slouch.) It is a relatively complex system that requires quite a bit of understanding of both archetypes and mathematics: to understand a birth chart you need to see the entire configuration (not just sun sign), evaluate the geometry and the archetypes, and also be able to compare against the current configuration (among other things). To me it seems much more plausible if you accept (as I do) the "holofractal" model of reality, i.e. that we live in a holographic universe where everything reflects everything else. As above so below as the saying goes.