I once had "The secrets of the black arts" on tape and I thought it was really good. Now I have "Vobiscum Satanas" on vinyl and it's also good, but I got tired of it after 5 plays or something as it's so monotone. All the riffs sound the same, the songs are arranged and structured the same way and the tempo and their breaks/changing to other riffs/parts are always the same! On top of that they haven't changed/evolved one bit since "The secrets...". I'm not saying that they should play a different type of music now or sell out or shit, cause I hate that, but they could have evolved a little, just like Opeth for instance have.
On top of that, I think it gets a little corny always having lyrics like "Satan, you're my best friend", "Lucifer, I love you", "Belial, you're my master and god" and stuff like that. I recall looking through the lyrics for the "The secrets..." album and as far as I recall there wasn't one song that didn't mention Satan (or some other name for Satan). Pretty inventive!!