What do you think about heavy metal music?
I like it.  You can't go wrong with the aggressive style of Metallica
I don't think I have ever really listened to it.  Is it alot of screaming involved?
Not a lot of screaming, but it's a fast temop and agreesive style.  
more heavy on the instrumental side then?
Screaming (music)
Screaming is an extended vocal technique that is mostly popular in "aggressive" music genres such as heavy metal, punk rock, and noise music. In heavy metal, the related death growl vocal technique is also popular. Intensity, pitch and other characteristics vary between different genres and different vocalists.
Genres.
Genres Classical and experimental music.
Although screams are often suggested in stories performed in the grand opera tradition, they were never performed literally, always being sung. The first significant example of
approach. A friend of mine, he said it sounds like 'Painkiller', but faster. So I can't think of another song that's quicker than 'Painkiller'. So if you define heavy in terms of speed, it's a pretty heavy track, it's pretty full-on."
Halford describes the album's title as "the fire and the power of heavy metal music", mentioning the band's other titles such as "Screaming for Vengeance, Defenders of the Faith, British Steel