One of the founding fathers of hiphop, Grandmaster Flash is arguably the world's first true turntable scientist. He was the first DJ to master cutting the breakbeat on a record back and forth, invented cueing through headphones and, with his "clock theory" system of orienting records on the turntables, the lingua franca of the modern DJ was born.
Back when Flash was the king of the Bronx at the dawn of hiphop in the mid to late '70s, it was all about the DJ, not the MC--without a soundsystem and records, there was no party. It wasn't until "Rapper's Delight," and the realization by record companies that hiphop could be profitable, that the balance started to shift towards the MC, with radio airplay generating far more capital than parties ever could. This decreased the prominence of the DJ to the point where, on almost all hiphop records at the time, studio bands were used to recreate the DJ's mixes--no turntables were involved.
It was only on 1981's Adventures of Grandmaster Flash on the Wheels of Steel, a live freestyle hiphop mix accomplished with three turntables and skills alone, that there was anything remotely resembling Flash live at a jam at the T-Connection or the Black Door. Granted, compared to wizards such as Mixmaster Mike, "Adventures" is child's play, but as a document of the origins of turntablism, it is unparalleled.
That said, Flash's new release, Essential Mix: Classic Edition, blows. It's basically a mix tape of classic cuts that Flash used in the early '80s, played back to back, transitioning from one song to the next, with a couple of scratches here and there to break the monotony. Your money would be far better spent on a ticket to see the Grandmaster live at Ohm this Saturday, where he'll show his real skills and rock your shit out.