I got to watch one when I was doing my internship in laboratory medicine. It wasn't bad. It was pretty messed up because they found out that the guy actually choked to death on some corned beef hash and potatoes instead of Alzheimer's like they thought. That's been eons ago and I can still remember this dead man's face!
I walked away impressed that surgeon's can actually know what the hell they are doing...it wasn't all nice and neat like in the anatomy books!
I was surprised that this didn't upset me but watching a bone marrow on an elderly patient was much, much worse. I had to leave the room with that. I don't know what upset me so much about it.