On one level, Slipknot appealed to the lowest common denominator and offended purists with their legions of 13-year-old fans but, really, isn't heavy metal for alienated teenagers to begin with? Besides that, the band's mall-busting radio metal has always had more going on than meets the eye. Death metal, rap metal, the early days of metalcore, nu metal, groove -- there's a lot in here. Iowa was a massive record for these guys both commercially and (kind of) critically. This anniversary edition includes a bonus live disc -- the legendary London "Disasterpieces" show from 2002.