The Castlevania series went through a number of growing pains during it's early years. While it's common for games in a series to be released one-after-another with little in the way of major changes (just look at the Mega Man series for evidence of that), Castlevania series saw four quick titles released one-after another, none of which really resembled each other. Sure, there was a dude in a leather like using his whip to fight the hordes of evil, but whhile the first game was a run-and-kill platformer, the official sequel was an explorational proto-Metroidvania game, plus there was Vampire Killer which seemed more interested in being the next Legend of Zelda game (which, ironically, even Zelda II seemed to have no interest in).
And then there was Haunted Castle Like a kind of mashup of Castlevania and Altered Beast, the game featurd six beat-em-up-style stages where the hero (presumably Simon) went against wave-after-wave of the under all to get to Dracula. Sure, he has his whip, and he has his sub-weapons, but the Simon in the game doesn't play at all like he did in his other games, nor is the pacing at all like the normal Castlevania games (which is weird sinc a real port of the original game, Vs. Castlevania was put out in arcades showing the original formula worked). It's almost like the creators behind the series didn't trust that the original formula could be replicated to great financial effect, so they felt it had to be changed drastically time-and-again.
On it's own merits, without the confusing back story, Haunted Castle is still an odd duck. It's brutally hard, more so than even your normal classic arcade game -- it just felt like a game daring you to play it, to see if you could ever make any progress. Couple that with muddy graphics and a slow pace that didn't encourage the kind of light, twitch-based gameplay the series is known for, and Haunted Castle just pales in all comparisons.
It's no wonder, then that it took many, many years for the Castlevania series to really come back to arcades again (with the creatively titled Castlevania: The Arcade) -- this is just not an easy series to effectively bring to the differing gameplay needs of the arcade format.