I dunno... the vast majority of heavy metal instrumental work sounds nothing but cacophonic to me. If I want "stylin'" instrumentals I'll listen to jazz or symphonies. 
Well, that's a taste thing, which is completely inargueable.
But weird thing is, a lot of people who listen to heavy metal in their youth start listening to jazz or blues when they mellow out, due to the similar complex nature of the music.
But as with almost any genre, there are also a few bands out there they have a very simplistic style or sound.
And I suppose the lyrics in the songs could very well be cerebral... too bad 90% of the time you can't understand them. 
That again, depends on the band and the singer. Lots people who actually growl and it's still somewhat coherant.
Having said all that, there are a few heavy metal/hard rock singers/bands I find palatable, even likeable, although I suspect the heavy metal crowd would sneer at my choices. 
Well, that's a taste thing. I'd never expect someone to like Metal just because I do. But to say that they're not talented is a ridiculous suggestion. The guitars and drumming can sometimes be phenominal, if not mind boggling.
