Slayer have one of the most diehard fanbases in metal history, and in some ways, they're also the ultimate band's band. Intensity begets intensity, and you'd be hard-pressed to find a metal musician out there who doesn't love at least one Slayer record.
I like the weird time signature at the beginning. They were so gnarly back then. I've always been a huge Metallica fan, and Slayer in a way were all the things that Metallica weren't and vice versa.
Slayer back then did the most evil riffs ever, and there was just something genuinely hostile about them. There's not one happy note in there. And their lyrics were really cool, and their imagery was really cool, and they sounded great and played great. That early era of Slayer was definitely one of my favorite extreme metal eras.