Look up, look down, to the left, to the right, turn 360° - you look around just in the same velocity as you turn your head.
I do not have the headset for this (though I'm planning on making one), I cross my eyes to make it 3D and it works amazingly well. It takes a bit to get used to, but it's awesome when you do!
This is the best app I made one and it works grate for it