Sounding a bit like Neurosis covering This Will Destroy You, MotA plough a post metal furrow that has become increasingly cluttered over the last half decade or so.
They should not confused for mere bandwagon-jumpers or copyists, however (despite my lazily comparing them to two other bands). Whilst it would be hard to argue that they are doing anything especially innovative or groundbreaking with their music, it is equally hard to find anything else that sounds exactly like it. And what they do, they do so well...
The word that keeps springing to mind is 'beautality'. I refuse to use it as a) it is more than a little pretentious, and b) it is not even a proper word. The fact is that Mouth of the Architect seem to be pretty much furious about everything, all of the time, and make a lot of noise to support this theory. But dig a bit deeper and pay some attention to the lyrics (such as can be made out) and themes of their songs, and it seems that they are driven by frustration and despair more than fury; and beneath all the howling and the bellowing and the sound of a bunch of 10 ton bearded metal guys destroying buildings with exploding guitars, there is a sadness and frailty. Like a bunch of 10 ton bearded metal guys destroying buildings with exploding guitars, but having a bit of a cry and a shout while they do it.
That probably makes no sense whatsoever. Listen to the last two and half minutes of Baobab for a more practical demonstration.