I must admit it's not something I believe in myself, but I've got a couple of friends who're seriously into astrology. You mention any of the 'celebrity' astrologers or the ones who do daily horosocopes for the papers to them and they practically spit on the floor and condemn them as charlatans.
The books with all the data about planetary postioning etc are updated regularly, taking precesion into account, so if you go to a 'reputable' astrologer, you should get a decent chart, based on more than your sun sign. I must admit, I was suprised by a few of the comments made about my chart which weren't the usual Barnum statements.
Off on a slight tangent, one friend has a theory about Venus in Libra being a potential gay indicator, because almost every gay person she knows has that in their chart. I don't, so maybe I'm the exception.
She drew my ex's chart, and said it was scary. If I remember rightly, everything except Saturn was all in one quarter of the chart, and Saturn was at the opposite side. It certainly could have explained a couple of things about my ex.
As I say, I'm not a believer, but occasionally, I think there might be something in there. However, the sceptic in me says that statstically, the predictions have to be right from time to time. Who knows, maybe one day I'll find the answer.