People generally agree that Harmony of Dissonance was not very good. In fact, it's the worst of the three GBA Castlevania games. It also happens to be my favorite of the three games. I'm weird like that.
The plot of the game, which is disturbingly similar to the plot of the previous game, is that three people have entered Dracula's Castle. One person is Juste Belmont, the hero. Another person is Maxim, who starts out as Juste's friend, but gets progressively evil as the game goes on. The third person is Lydie, who is being held hostage by Dracula and needs to be rescued.
There's also a subplot about amnesia, but fittingly enough, I don't remember what it is.
The best part about this game, hands down, are the graphics. It has super-fancy graphics, and everything looks great. I like the graphics, but I think it's kind of weird that they gave the series a complete graphical overhaul, after only one game. It's especially weird, because the graphics were a high point in the first game, so they didn't need to be revamped.
Despite the new graphics, most of the enemies and locations are copy/pasted from the first game. This is either going to strike you as a staple of the series--"Every Castlevania game has to have a tower filled with clockwork gears!"--or as laziness on the part of the developers--"I have to fight bat enemies again?". In fact, the only place that I can really remember that was new and different was the skeleton level, where everything was made out of bones. You have to fight giant spider skeletons, and there was a room with a huge Pit and the Pendulum-style pendulum axe, and the skeleton theme was done so well that I made no bones about it.
I like the fact that they basically doubled the number of boss battles in this game. People complain that the boss battles are super-easy, but I didn't think that made them any less fun. And sure, some of the boss battles used the old "let's take a normal enemy, but make it bigger and call it a boss" technique, but that didn't upset me either. Who cares if Giant Bat is the same as a normal bat, but giant?
In fact, this boss creation technique resulted in my favorite boss battle: the one against the blob enemy who's made out of jelly. They have the normal blob enemy expand, until it fills half of the sceen. Every time you hit the boss, it gets smaller and smaller, until it reaches the point where it becomes a normal-sized enemy again. At that point, Juste puts the jelly enemy on some toast and eats it for breakfast. It was a deliciously good boss battle.
If I had to complain about this game, I would use the classic "it's too short" complaint. This game feels a lot shorter than the previous one. This is in spite of the fact that the game has a dual overworld. So basically, you play through the entire castle twice, once when it's the "good world", and once when it's the "bad world". And the game still feels kind of short? That's a letdown.
Other complaints I would have about this game include...
- Replaying the game as Maxm is almost impossible to do, because he can't get any life upgrades, so you're stuck on Level One for the entire game. And half of his moves are complicated combos like "press A and B, then up, down + A, left, R + L, R + A + B + Down + Left, then B". None of these combos are described in the game. You're supposed to figure them all out on your own.
- There is no reward for completing the furniture collection sidequest. Its only purpose is to waste your time.
- The game has multiple endings, which is good, but figuring out how to unlock them is confusing.
- They got rid of the DSS card/magic system from the first game, which I really liked because I would abuse the "stand in place to be healed slowly" spell. They replaced it with the subweapon system, which I never used.