I have just looked at this concert film on Turner Classic Movies. There have been a lot of concert movies running on that venue recently, and I run the risk of overdosing on them. Nonetheless, it was there, and it look at it.
First, I need to note that I am not the core audience for rap music. It's not my music at all, even though I can link it to the talking blues and recitative. The simplicity of its music and the crudeness of its language both bore me. So, can I place myself in the dual position of one of this show's audience, while standing far enough outside to judge its inherent value? You be the judge of that.
It is mostly a stage show, and an obviously and carefully plotted one, that makes its performers and the artists that walk onstage for an 'impromptu' rap battle look far less than spontaneous to my eye. Clearly, however, the theater audience doesn't care, and it's their energy that is infectious, energy that breaks through the constrained pace of the rappers.