I've been administered propofol before, and I've experienced syncope before. They're a great deal alike. If anything, the most notable difference is that propofol takes long enough you can feel it coming on, which is more than I've ever been able to say for old-fashioned passing out.

I don't find anything to choose between the experience of coming out of it and that of waking somewhat slowly from deep, dreamless sleep, except incidentally that one typically falls asleep and wakes up in the same place. The discontinuity of awareness "feels" the same in both cases. For that matter, going under propofol feels a lot like falling asleep while deeply exhausted, except without the actual exhaustion, which is in my view the strangest thing about it.

In my mostly misspent youth, and long prior to my first experience of general anesthesia, I once had occasion to try what was then and might still be called "whippets", or the inhalation of carbon dioxide for theoretically recreational purposes. Stupid and pointless as this is and was, in hindsight it was much as if one were under propofol able to pause just before the point of entering discontinuity of conscious experience. That was deeply unpleasant in a way I find impossible to explain, but enough so that if forced to choose I believe I'd prefer to undergo surgery again. As with being around heroin addicts whose habit one does not share, it's the sort of thing that should quickly, and quite rightly, lead one to decide that a scene where this is ordinary is a scene where one does not wish to belong.