Neverfly and I have ridden a roller coaster with such strong g force that we both began to lose consciousness in one part of the ride just before it stops half way through only to take off again reaching the same Gs again. It was a strange feeling for me to not be under any sedation yet to see everything going dim because, I'm assuming, the blood was being pulled out of my brain. Then of course when we stop the blood comes rushing back and the lights come back on.
But having been clinically dead before, it's not that spectactular. A quick hallucination before it all goes black and all is peaceful. Kinda like when you sleep really hard and have no recollection of any dreams. Its like you didn't exist rather than having slept well. I am guessing that is what death feels like. Nothing.
That would be my assumption: "A quick hallucination before it all goes black and all is peaceful." We would hope for such a demise. My thought is, what happens when you know you're near the end? Those that I've witnessed were all unconscious.