These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Complete Monster: Walter certainly counts. Even before he is revealed to be a pawn in Mathias's plan, he still kidnapped Leon's betrothed and held her as a hostage. When she is rescued, and all seems to be well, she is suddenly revealed to be succumbing to vampirism given to her by Walter. Leon is left with no choice but to kill her before she turns. The reason he does these things? He's bored with his eternal life, and likes playing games.
Draco in Leather Pants: Despite his tragic backstory, Joachim seems to be a bit more endearing to the fandom than he should be.
Ensemble Darkhorse: Joachim, whose vampire-ness, prettiness, and unique fighting style have made him relatively popular (Though not enough to make a re-appearance...yet.)
Good Bad Bugs: The Item Duplication Glitch in the North American version.
Ho Yay: Lots. Just try listening to Leon and Walter's conversations and not pick up subtext.
Magnificent Bastard: Mathias Cronqvist, Dracula's previous identity, counts as one, since he pretends to be bedridden but is actually planning to become the immortal vampire by pulling the strings behind the scenes.
The aforementioned Bonus Boss, as well as the general atmosphere of the area leading up to it.
Leon's best friend in the universe, whom he trusted above all else, has betrayed him, used him, and doomed his fiance to a horrible fate, all to become a godless abomination as revenge on God for his own wife's death.
Medusa's frozen expression, face, and overall appearance is quite striking.
That One Attack: Crazy Mode really brings out the worst moves from the final bosses.
Walter's "Behold my strength" attack will now not only blast your health, but he will continue using it until you hit him. The catch? He can use it again before you can reach him, putting you in the blast radius. Unless you have the Wolf's Foot or Invincibility Jar.
Death gains a homing double-attack that he'll start spamming if you are too far away from him (when you hear him yell "Die!" things are gonna suck), Deadly Tempest unleashes two more waves of fire, and there's a new attack, in which Death says "it's over," and throws an energy ball to the center of the stage, resulting in what is basically Demonic Meggido, nuking the entire screen with an unblockable wave. Good thing you can Perfect Guard!
The final phase against The Forgotten One removes the rocks that protected you from his Breath Weapon in the normal mode, and you can only dodge it with precise movements.