The following bands are not overrated:
Black Sabbath - anyone who thinks so is wrong. Their first 6 albums rule.
Megadeth - Rust in Peace, Peace Sells, So far so good, Killing is my business, overrated, I think not, given the fact that nearly every faggot on this board hates them just because they dont like dave mustaine, and thats despite the fact that one of their albums is probably 50 times as good as most of the worthless shit that is produced.
Death - people write death off as being derivative rubbish or "sell-out unauthentic" death metal. this is despite the fact that they listen to a hundred different derivative black metal bands who can't piece two different riffs together, produce the same album every 3 months and have done fuck all for black metal (let alone music).
Primordial - no. that's all that needs to be said.
Slayer - greatest band of all time. so no.
and there are others, like the chasm (which retard mentioned them?), watain, testament etc.
I also agree with the following being overrated:
SYL
Anthrax
Deicide
and I'll also add Edge of Sanity, Devin Townsend, Pink Floyd (although again not metal, but they are fucking crap and are often referred to as major influences on metal bands) and Entombed.