I haven't. Most that happened to me was fainting for about 15 minutes. If death it is like that, then nothingness is a perfect way to describe it.
If you search for NDE (near death experience), you will find all kinds of stories of people who "died" and came back. Some say they saw the truth, angels, devils, etc etc. Personally, I think that is just the human brain going haywire since it is quite literally dying, so people "see" all kinds of weirdness. But maybe I am wrong, and they truly did see things that we can't see while alive. Maybe the truth, or their personal truth, at least.