Extremely uncomfortable, to say the least. I found myself continuously trying to relieve the stress pain in my arms and shoulders, hips and thighs. While the cornu provided good support, having that rubber phallus fully inserted in my rectum, while not painful, caused my prostate to ache and throb due to the pressure and gave me a stiff erection with steady spurts of precum that felt like a dribbling urination. That was a new experience for me as precum is usually a predecessor of ejaculation. This dribbling was continuous, except when I lost control and emptied my bladder involuntarily, about midway through the crucifixion. I think my movements/struggles while hanging on the cross tended to apply pressure to my prostate from the cornu, but not enough to make me cum, which was torture in itself.
When I was untied and taken down I was exhausted and very weak, so much so that I couldn't walk and had to be carried over my MASTER'S shoulder. I didn't get my land legs again for several hours and my shoulders, legs, chest and rectum were pretty sore.