Slow, heavy and atmospheric is the formula here. At times the music does get faster, but even the fast parts aren't even super fast. There is a lot of clean guitar playing in the background, especially during the solos and slower moments and it really adds to the feel of the album. The tone of the guitars is pretty interesting in that it's not very "heavy" sounding but still manages to actually BE heavy. The use of a few different styles is also intriguing; the music here ranges from almost pure death/doom to blasting black metal to somber and gothic moments saturated with mournful keyboards, and in a few cases all three of those styles are interwoven with fantastic results. A weaker aspect of the music is the production, specifically the drums; they have no power whatsoever and when the toms are being pounded on in slow and steady fashion it comes off as amateur sounding. The bass and snare sound fantastic, but there's just no power in the toms.
The vocals, by Martyr, are fantastic. His low, guttural growls are some of the best I've heard in metal and his higher pitched screeches sound absolutely depraved. His baritone clean vocals, while probably not technically "amazing" fit the music perfectly, especially on the third track, "Depressed," where used with mournful piano and guitar create a truly depressing feel.
The weak point of this album, unfortunately, are the lyrics. Christian in nature and English by what appears to be very poor translation from Norwegian, they are so poorly worded that they almost sound comical at times. I don't blame the band for not being English scholars, but some of the lyrics are downright laughable. Skip over the liner notes if you want to continue taking the music as seriously as it wants to be taken.
What I find most interesting about this album is the mix of styles, in an era where this was far from commonplace in the metal scene. Like I said above, goth, black, death and doom metal all come together on this album in such an almost perfect way it's almost strange and to my knowledge rarely if ever used by bands of the day. While this is a pretty normal practice today among metal bands, I think I give Antestor credit for being among the (if not THE) first to combine all such styles in such a good way.
Highlights of this album for me would have to be "Depressed," with its gloomy keyboards and dark vocals; the title track/instrumental with it's brilliant drumming and use of clean guitars and transitions from blazing fast to slow and somber; and the closer track, "Mercy Lord," which while having a rather awkward opening minute and a half or so builds to a brilliant black/death/gothic/doom masterpiece complete with soaring female vocals and organs. "Mercy Lord" definitely ranks as one of Antestor's best songs and is a powerful way to end to the album.
Martyrium stands as the debut album of a brilliant band, and while not a perfect album by any means, there is enough good music here and enough interesting style and combinations of styles that any metal fan should be more than satisfied by this record.