Nearly as good as the first Super Mario Bros, 2 refines the level design to take the mechanics of the game to their logical conclusion without edging into the territory of "Kaizo hack". This is still a standard Mario game after all, and you won't find the strict unyielding requirements for movement you would in a contemporary hack.

What you will find are brutal enemy placements, difficult jumps, and a sort of winking elbow to the shoulder from Nintendo. This is a game to be played only if you have truly mastered the original, and stands as a sequel with a difficulty curve ethos towards player progression that you don't see often these days.