Everyone's ICD has different settings as to voltage, pacing, etc. Some need stronger jolts than others. I think most will agree that the surprise and suddenness followed by the anticipation of one or more following shocks is greater than the actual event. It's done and over with about the time you start to question what just happened. Nerve wracking, yes, but what are the choices?
The shock is so sudden that it can be more scary than painful. Some people feel that it is very painful while others say it is very uncomfortable, not so painful. It is different for everyone. But most will agree that it is not pleasant.
I felt more than one sensation, first I felt an electrical feeling followed almost instantaneously by a crunching sensation and burning pain simultaneously. It was very short lived but the electrical feeling lasted a couple seconds after the pain was gone and shot down my abdomen and arms. I was stunned and the pain was intense but so short that it was bearable.
Better than the alternative :)
My husband has had it go off two times and he say's it like a kick in the chest