I don't think I've heard enough of Jay-Z to rate him, needless to say what I heard of him didn't appeal to me. I'm more into rappers like Necro, Ill Bill, Mr. Hyde, Sicknature, Lord Lhus, Jus Allah and Sean Strange..
In mainstream success, Jay-z is one of the best. As far as actual rapping, and lyrics? That's where he's overrated. It's hard for me or anybody that listens to rap to say Jay-z is a better lyricist than rappers such as Eminem, Nas, Biggie (when he uses most of Big's shit anyway), etc etc.