One of the most overrated metal bands, in my opinion...
Children of Bodom.
Now, I can't stand when people equate overrated with "They suck"...Children of Bodom is a really good band, I have a lot of respect for them and I like them. However, you can put on any of their cd's and count the Iron Maiden riffs. I know that saying that's becoming classic "we're all playing (insert classic metal band here) riffs"...but there's a difference between obvious influence and copping a riff. I'm sure there are people who will disagree with me, and there are probably more overrated bands out there...this is just my opinion of course, I just hear a lot of people going on about how original c.o.b. are.
OH, and even though I don't really consider them a metal band, I second that about KISS...nothing special, unique or particularly intersting about them other than the makeup. Catchy songs, I chalk them up to basically being shock-pop.