Just finished Super Castlevania IV! I am... glad it wasn't a very long game, I think I'm convinced at this point that Classicvania isn't necessarily my kind of thing. I've heard everyone talk about how good this game is, but I felt it was way too punishing and got to the point where any minor mistake I made as I played either instantly killed me, or it was a rare occasion where I somehow didn't die, but would lose most of the progress on the screen I was on. By the time I was two-thirds of the way done, I was already waiting for it to end. It seems like a game that would be a lot of fun if you really put in the time and effort to get good at it and memorize all the roadblocks but... I just don't think it's my kind of thing. I played it to completion just to say I did so.
Edit: I checked out of curiosity, and it took me about 4 hours to play the whole thing start to finish.