While I think this game's visuals and soundtrack remain untouched by most other 2D platformers let alone another Castlevania game, I think a lot about the gameplay just doesn't age all that well.
The game's difficulty feels pretty decent for maybe half of the pre-upside down castle. At a certain point though, Alucard just becomes too powerful and there really isn't anything that can really challenge him without actively restricting yourself to make the experience more challenging. I can cut it a bit of slack since heavy exploration based games with levels were somewhat new ground and this not being what Konami considered the main Castlevania project at the time but it's still a for sure issue going back. I also cannot comprehend how anyone on staff thought equipping a healing item over a weapon slot to use it makes any sense. Also this may just be my personal taste, but I've never been huge on the Iga-vania "do a semi-esoteric thing in the fake final boss to unlock the last third of the game" thing.
I still think this great game full of fun experiences well worth doing at least one playthrough in your life. Just not my favorite Castlevania game.