The unforgiving jumping controls take some getting used to when you haven't played this in awhile. It made me wonder how I was so good at this game as a kid. It's annoying when you jump from a platform and you're not quite far enough to the right and you miss and die. That kept happening to me on the second stage. Or you accidentally fall down the stairs. Or a a Medusa head knocks you off a small platform (thank goodness for that shortcut in the second stage where you can use a Medusa head to bump you up) or a damn fishman or bat knocks you off a platform.. The control isn't as polished as other NES games which adds to the challenge.
With some practice I made it to the last stage before Dracula's castle without a game over, and then I burned through a bunch of continues trying to remember how to get past the bats and then the hunchbacks (use the clock). Dracula himself isn't that bad once you get the hang of jumping over his fireballs and whipping his head. Then just toss holy water at his second form to slow him down.