The first time I heard Opeth was on a heavy metal/hard rock compilation. The song was "Benighted" (it was weird to me that an all acoustic song was on a metal compilation at the time, until I bought "Still Life" and realized it was the shortest track at five minutes by about two minutes). I immediately went out and got "Still Life" because Opeth stood out by far from anything else on that compilation, and "Still Life" is probably still my favourite (this is probably just sentiment as it's my first Opeth memory, I was so excited that I "discovered" them). Here in Australia, because we don't really have a major metal "scene", publications, radio, specialised metal stores, etc., you pretty much rely on word-of-mouth and have to really look for new bands.
But enough of me crapping on (I'm new here, I have a lot to say and have missed a lot of threads), in regard to Mikael's comment, yeah sure, I can see where he is coming from. "Drapery Falls" (an edited version anyway) was their first single, the album had a producer known outside of metal circles, etc. Although I have noticed, even the newer fans who discovered Opeth post-"BWP" still love the older stuff just as much and wish they had found out earlier.
That's the great thing about Opeth and why they haven't fizzled out like, for example Dream Theatre (I do like DT, they are one trick ponies, but they are great at what they do). Opeth's catalogue is so varied and has evolved so that every album is so different and challenging to listen to. Each album has something different and fresh. And that whole "Roadrunner" arguement is so old.