I first became interested in metal after being introduced to the band Nightwish sometime in 2007. It was all downhill from there. Songs like "Slaying the Dreamer" caught my attention more than the more symphonic elements of their catalog, and so I started to search for heavier music. I became interested in Metallica, and have remained a fan of their earlier work ever since. After Metallica I still yearned for something heavier, bleaker, and more "metal" (as the cliche goes). I didn't understand how people could love death metal as much as they did, but I forced myself to really sit down and try it. After getting used to the cookie monster vocals, I gained an appreciation for the music for what it was. Recently I've started delving into the black metal scene after not being able to fully appreciate its own charms.
I often prefer music with a slow tempo as it allows the riffs more room to "breathe", as it were. This isn't to say I dislike fast music - I wouldn't much like thrash, death or black metal if I didn't - but I usually prefer bands like Samael or Suffocation to something like Emperor or Origin. Again, I do like fast music, so long as it's not a blinding blur of speed - my favorite album of all time is Cryptopsy's None So Vile, for gods sake. Tempo changes are necessary, and using blast beats for an entire album is more indicative of a lack of ... well, I won't say skill, but I will say creativity.