It's reported to be 50 minutes long. I think 777 succeeded so much due to the heaviness and that there was absolutely no filler; even Unendlich sounded like a part of Black Mass. Then again, Circle of Snakes didn't have any filler and was heavy, so...

Anyway, I loved 777, CoS and Deth Red Sabaoth (NetherBound, Black Angel, White Angel, Deth Red Moon, Pyre Of Souls: Incanticle, Rebel Spirits, SkinCarver, The Coldest Sun, Without Light, I Am, I Luciferi, Halo Goddess Bone, My Darkness, Skull Forrest...) all amazing. The only ones I don't care much for are Wicked Pussycat and HellMask.