We actually get to see The Gate...
and it looks like a desert. With no demons. And some sort of stone altar and a chimney producing smoke.
It would have been awesome to see the Gate with a bunch of minions running around and other kinds of demons too. Maybe even some of them with wings and everything is just chaos and darkness but no instead we get a desolate desert with some rocks and stone and then a stone staircase. How lame.