There's been rap I enjoy, but it's rare, and a lot of what I have enjoyed focuses on attacking rap music and the culture surrounding it, though some of it does deal with other themes such as religion, philosophy, culture, life stories, etc. For the most part, I just don't enjoy the style. The vocal style isn't appealing to me. The accompanying music often makes me wish I was selectively deaf. And then the lyrics very often present its themes on drugs, crime, sex, materialism, and partying in ways I find unappealing at best and despicable all other times.
Again, it isn't that I don't think rap has potential, as there is some I've heard that is very appealing. However, I find the "bad rap":"good rap" ratio to be so high, that I generally just don't bother with the genre. Not to mention, even the songs I do like generally lose my interest after a couple of days, and I rarely ever take note of the artist for fear that the rest of his songs will just be the usual trash that gets thrown my way (pretty much everyone I know loves rap, so I'm forced to listen to it a lot while in group settings).