I went to see them at Bristol's Cooler last week. The band were epic, the crowd rapturous and the entire experience utterly life-affirming; despite my getting kicked in face so hard by a crowd surfer that I couldn't eat properly for two days.
A somewhat pretentious band name and an absence of vocals naturally leads to accusations of post-rockness; and certainly in the early days there was more than a whiff of Pelicanesque riff-heavy soundscapes mixed in with more intricate Red Sparowesey guitar twinkling. But the tedious predictability of the quiet-loud post-rock-by-numbers template (I'm looking at you, Explosions In The Sky) just isn't consistent with ASIWYFA's output. They don't feel the need to dick about slowly building up to an epic sweeping crescendo; instead they go straight to epic, and then build that up into supreme Godzilla-sized epicness. And as they continue to grow and develop their sound, they become ever harder to define.
So I'm going to give up trying.
Go watch them live instead. It's the only way you'll understand.