Going strictly by the Amazon rating system, I give this 4 stars: I like it. I'll need to be in a particular type of mood (probably late night or early morning) to want to listen to this, but when that mood hits, Messe is ideal.
It begins in darkness and maintains that throughout. The first track, which puts me in mind of early Godspeed, is underpinned by the sounds of warfare - you can hear the quiet roar of jets and the percussion of automatic weapons, all of which sits just underneath the surface of menacing strings which gradually build and build.
It's a piece of music that has to be listened to as a whole. It's subtle, and it's musical, but I would never describe it as an 'easy' listen. I don't think it's meant to be, though. It's not background music, but to describe it as 'challenging' would be to do it somethinig of a disservice.
If you like GYBE or other bands of that ilk, then Messe is well worth a listen.