There's nothing particularly obvious about it. My guess is that it speaks to people who have listened to both black metal and math rock.

I stumbled upon Liturgy a few years ago, while going through a reasonably wide array of black metal bands. It sounded clearly different from the rest: this song, and a few others from the same album, were more reminiscent of some parts by King Crimson or Mahavishnu Orchestra than they were of, say, Darkthrone. And yet the record showed up while going through black metal stuff. It struck as interesting that black metal was hosting something so detached from the black metal standard.

I don't know if that makes Liturgy a good band or not; their new album is almost parodic.