I love it. I think most of what you say is accurate (but draw the line at Manowar parallels). It sounds exactly like Mastodon, and at the same time doesn't sound like other Mastodon albums. Slower, more deliberate, somehow more cohesive (smooth transitions in sound/tempo from song to song). I think that what the instruments are playing underneath those relatively melodic vocals is satisfyingly weird and intricate. Some of the lyrics seem pretty dumb.
So well informed I don't know where the truth begins.