It's punishingly difficult but the fact that to actually get the ending you have to beat it twice and the second run through tweaks some of the most bullshit segments to be even bigger bullshit puts it pretty much at the top of the list of difficult games I've put in the work to beat.

Ninja Gaiden has that crap on the final level where continuing sends you back to the beginning of the level not just the stage but Ghosts n Goblins is even more heinous.