In it's prime it offered a generation dulled by crappy rock an alternative that focused on vocals and low key instrumentship. One could really dissect the structure or layers of a song. Tops is Eric Clapton who was the first I actually saw that was actually unplugged.

At least during the nineties when I would watch it, this was a good show for creating so many intimate live performances by leading artists on film - among my favorites were Nirvana, REM, Bjork, Alice in Chains, The Cure, Stone Temple Pilots and Tori Amos - although I've always thought the concept to be a little arbitrary. Technically, many of the instruments were, well, plugged (for the pickups), some of the artists play accoustic anyway, and the distinction from electric is a bit pointless.