KRS-One's impact on rap music and hip-hop culture can't be overestimated, as he'll be the first to point out. With Boogie Down Productions and as a solo artist, he helped invent gangsta rap, pioneered the concept of "edutainment," was instrumental in bringing a sense of history and social consciousness to hip-hop, and brought the genre from the streets of New York, where he famously lived as a homeless teen, to the halls of Ivy League schools, where he has just as famously lectured. His insistence on proclaiming himself the conscience of hip-hop would be irritatingly self-aggrandizing if he didn't have such impeccable credentials for the job. After parting ways with longtime label Jive, he took a break from recording in the late '90s, returning with 2001's independently released The Sneak Attack—which, contrary to its title, waged a full-frontal assault on rap's misplaced values, reinforced by beats that weren't just old-school, but damn near prehistoric. Making up for lost time, Spiritually Minded and The Mix Tape quickly followed, and now the stripped-down, uncompromising Kristyles offers another retro manifesto from the self-described blast from the past. Often didactic, always passionate and blunt, KRS-One started tilting toward the education end of the edutainment equation a long time ago, and his own importance forms a major component of his curriculum here. On "Underground," he even gives his listeners a badge of underground authenticity for listening to his music, but such pandering moves should be beneath him. Since his return to recording, KRS-One has grown predictable, and Kristyles is far from a career peak, but there's something touching and inspiring about the rapper, producer, and activist's lack of irony and self-consciousness. At his best, he still exudes righteous indignation and moral authority, and at his worst, he sounds like an anachronism railing against times that have passed him by. Once one of hip-hop's most revolutionary forces, KRS-One now occupies a place somewhere between "hip spiritual leader" and "cranky uncle." The more hip-hop changes, the more he stays the same, which on Kristyles proves both a major strength and a frustrating weakness.