I actually disagree with his stance on Castlevania 3.
I've been playing the game recently, and I think it's a masterpiece on nearly the same level as Super Mario Brothers 3.
All of the issues he encountered were mostly non-issues with me. I agree that the stairs can be a pain, as the whole "you'll have a hard time using a special weapon on the stairs" thing is pretty much true. And, yeah, there are those parts like in stage 5A and stage 9 where you have to fight dragonheads (or whatever they're actually called) as you're climbing stairs. That's tough, but it's not impossible to master the timing and the stair movement that the game requires to make those sections reasonable.
But honestly, that's just it. If you're both patient and skilled in general, Castlevania 3 is actually a game of only moderate difficulty, especially when it comes to bosses. The toughest boss in the game is the doppleganger, and that's BY FAR. As for Dracula, again, the Nerd just doesn't know how to approach him properly. He's actually a much more reasonable boss than he was in the original Castlevania, even. The "pillar of fire" is very easy to avoid once you figure out how to manipulate it. That is, the more you move around (especially in the direction opposite of Dracula himself) the wider the outside pillars will be, allowing you to easily dodge the giant pillar and attack Dracula. His second form and third forms are relatively easy as well as long as you have the axe. I agree that it was dumb to send the player back to the beginning of the final level upon death, but that's all.
Putting a little bit of work into learning better patience and timing goes a very long way with classic NES games, and CV3 is not an exception to this.
And believe me, I'm not as good at games as I used to be. And, I still find the original Castlevania to be the hardest of the NES games, even though it's the shortest.
Castlevania 3 not only brought awesome innovations to the series like additional characters and branching paths, but it also had plenty of levels, an amazing soundtrack, and good replay value. It marks an astronomical improvement over the basic foundation of the original Castlevania.