Well, it really contains little that attracts me about music. Minimal (if any) melody, repetitive percussion (typically sampled or synthesized), little to no actual vocal talent, and generally uninteresting (if not grotesquely stupid, violent and misogynistic) subject matter/lyrics. NOTE: This refers only to what I've been exposed to (i.e. the mainstream) not the genre as a whole.
That said I don't actively hate it. I hate the fact that its shoved in my face everywhere because the record companies know that it is selling right now make sure people hear it everywhere. I also agree that, for the most part, it isn't actually what I would consider art because it requires little to no craft, skill, ability, etc. and is nearly totally devoid of any meaning or real emotion. Can a rap song really express the range of emotions other genres are capable of without melody or actual singing? I think not.
That said, I like the Gorillaz as well as K-Os but they both contain elements of multiple genres that I already like as well as a tendency to record with live instruments and are actually musicians. So they don't really represent the genre as a whole at all. Although I wouldn't say I like them in spite of their genre, it isn't too far from the truth either.
In brief, I don't hate the genre as a whole. What I do hate is the dominant sub-genre (gangsta rap) and the vapid commercialism, violence, misogyny etc. that defines it compounded by the way it is being pushed on us all the time.