As a rule, rap is only received moderately well on the SDMB. Some folks feel better if they make it clear that Rap isn’t music, etc. Totally cool to have your opinion; other folks feel the same way about Country, or Opera, or Metal.
But if you’re in the mood to hear what great freestyle rapping is, follow that link. Black Thought has no notes in front of him, and I have no clue what prep goes into this, but damn. It’s just cool and interesting - the words, the various cadences he uses as he moves from phrase to phrase, the simply breathing techniques going on. He totally pulls it off. I can see why it’s going viral in the hip hop community.
ETA: here’s NPR’s take on it - Black Thought Shows Off The Art Of The Unrelenting Freestyle : The Record : NPR