As far as slayer and metallica go, i think metallica is still good on the black album but after that they are just boring and terrible, but maybe i should give them a chance. With slayer, season in the abyss is great but after that they are much more boring even though they have good tracks. I still think "bloodline" overall is a creepy and good song, its too bad that they over-used that style on the later stuff. Overall, i think god hates us all is a good album, yet it's hard to compare their later stuff to the first 5 which were all just great.
EDIT: actually i think newer slayer and "load" by metallica are pretty good, maybe i'm just more open minded than i used to be. Also, don't really know why people are against the post seasons of the abyss slayer stuff...it might not be as good as the 80's stuff, but it appears that all their albums are decent.