-Illuminous Cavern (Harmony of Dissonance)
Ick, what? That's a terrible idea for a stage. That area was hands-down to most boring area in the game, had terrible music, and is probably the worst cave-like place in the Castlevania series.
Also, it bugs me that so many people hound down on Jonathan. I can understand distaste for his attitude, but he mellowed out somewhat as the game ran its course, and he's the only wielder of the Vampire Killer to also have a plethora of other items at his disposal.
That guy was also able to hold his own against Richter (Whip's Memory, though it's essentially the same thing), and he has a Wrecking Ball as a subweapon. That's awesome.
Charlotte was a little flat though, character and ability-wise. Though, some of her spells were wide-ranged and flashy. (Cocytus comes to mind, which is probably my favorite)
So yeah, I think Jonathan at least deserves to be in. He'd be perfect for that obligatory, useful character that bugs the crap out of opponents.