For a long time I've said this thing that Castlevania is one of my absolute favorite series of all time, and yet I'm not very good at them. It's held true for years. Another thing I've said for years is that I think Castlevania III is my favorite of the NES trilogy. Though I hadn't played it in over ten years now. So (stupidly) I bought it on the Wii U Virtual Console right before a physical edition of the Castlevania Collection was announced for Switch. Ugh.
Anyway, the things I had raved about was that Castlevania III took the things that made the first two games work on their own, and sort of combined them. So while it's a linear game in the way that the first one is, it had branching paths which made it a little less linear, but not quite as sprawling as Castlevania II. It also added new playable characters with different abilities. And of course, it had amazing music.
All of the above remains true. However, having somewhat recently replayed (and beat) Castlevania II, I know think that's my favorite of the NES trilogy. There's no denying that that game can be a jerk. It's often cryptic, yes. But it's AWESOME in its tone and its breadth. Back when I replayed it I called it a precursor to Symphony Of The Night and the many GBA/DS Metroidvania entries. And I stand by that.
Castlevania III tones down on the "where I'm supposed to go" and "what am I supposed to do" stuff, but ramps up the difficulty by just making enemy placement and the environment brutal. I genuinely forgot how difficult this game gets. I'll say this - I still think it's a great game, but I do think I prefer the first and second. And at least at this very moment, I'm getting frustrated trying to make progress in it the way I used to be able to.