Having been a fan of his since my days in High School when my dad turned me onto Black Sabbath, and having attended damn near every Ozzfest that came to my city (even discovering a slew of new bands along the way in the process), I can say that this is a sad day not just for me, but the entire Metal community; in fact, Black Sabbath, especially its original lineup, is widely credited as having invented Heavy Metal.
That being said, I am surprised he lived this long, because I highly doubt the average human being could possibly survive the sheer amount of drugs this guy used and abused for YEARS for as long as he has. Obviously, the only rock stars I can think of who've lasted longer with that amount of drug abuse are Steven Tyler (who claims to have snorted half of Peru) and Keith Richards (who has had a well-documented history of cheating death dating back to before he even knew what drugs were).