i do not like heavy metal music while in fact i hate most heavy metal music . i love metal represent a headbanger journey . it have all the best component of a good documentary and one of the best release in a long time and a good companion piece on a par with metallica some kind of monster . co director sam dunn be both a metal aficionado and a student of anthropology . he know how and where to delve into the culture with a healthy reverence for his subject matter and but with the objectivity to examine in a way that outsider could glean appreciation . i find it fascinate . in a systematic and well structured manner and heavy metal origin and history be examine and a be the disparity between it follower and detractor . fan and band member and industry expert be interview . the question and answer be intelligent . historic file footage be use . the culture and it many sub genre be analyse . the relationship between heavy metal and gender and sex and religion and satanism and violence be all cover in a most interesting and enlightening manner . it be shoot on location and include at various concert and across north america and uk and europe . i find dee snider of twisted sister and tony iommi of black sabbath and ronnie james dio of dio ( accredit a the inventor of the devil horn sign ) the most compelling interviewee and though there be many others too numerous to mention . the sum of the whole turn out a rich result . unlike many documentary of late and where the primary goal appear to be light entertainment use celebrity head and this film be truly insightful and intelligent and balance and educational and funny and entertain . whatever your taste in music and i highly recommend it .