Witchfinder General, one of the 'founders' of doom metal, and found out that they are pretty crap. Maybe because they were one of the first, but I would not really call their sound 'doom' by any means. The majority of their tracks are not slow (just slower then radio-songs), there are almost no drudging guitars, instead focusing on hair-metal guitar solos and riffs, and the overall feel of their songs was not depressing in the least. In fact I found almost all of their songs pretty dull and boring.
After going through their entire discography, the only album I would even bother a second listen on is their second full-length, Friends of Hell, and even that is sketchy (only two songs stood out at all). Their other two albums, Death Penalty and their reunion album in 2008 Resurrected, were both not worth the time it took to listen to them.
I get that they were one of the first, even in my impressive music collection (38,000+ songs with over 1,400 being doom) they predate any other band by two years, with their first release coming out in 1982. But even by '84 bands like Trouble and Saint Vitus were doing it better (ok I'm not sure about Saint Vitus, I haven't listened tot hat album yet, but I am sure about Trouble). Maybe if they hadn't have broken up after only two releases, they might have molded into something truly worth reckoning, but as is, they are easily forgettable, even among metal-heads.
So thanks guys, for putting the genre out there and giving other bands a hand-hold and an example, but really that is it. Your music is just going to fall by the wayside of other, better bands, at least within my collection.