Mellencamp's ambitious retrospective spreads 54 tracks over four thematically arranged discs, emphasizing his serious-folkie middle age over his heartland hook-maker youth. Two pre-stardom songs are represented in acoustic renditions, and Disc One ends showing how "Jack And Diane" evolved from a demo called "Jenny At 16." Several other hits -- including 2001's seeming Nelly rewrite "Peaceful World" -- show up in previously unheard versions. Guests include Joanne Woodward and Cornel West. So no, not your usual rehash. But his more free-wheeling Cougar-era obscurities deserve their own anthology.