Aria of sorrow is hands down, the best showcase of what the game boy advane is capable of.
Story - Pretty straight forward. You are Soma, a japanese student who is suddenly transported to draculas castle, and you kinda go from there.
gameplay - Pure tradtional castlvania/metroid gameplay. Unlock abilities to take you to more of the map. Unlock another ability after that, etc.
sound - No voice acting obviously, as this isnt a PSP game. Great Immersive music and great enemy and weapon soud effects.
graphics - best on the GBA. hands down, better than metroid, even slightly better than minish cap. so many immersive enviroments. great use of 3D clouds in some stages. Huge bosses. And my personal favorite, shell casings coming out of your handgun and bouncing on the floor, and rolling off the edge of the ledge. Why dont any other GBA games have this level of detail?
In conclusion, Aria of sorrow is a Must have game for you Game Boy Micro. And for something you can get in a double pack with Harmony of Dissonance, there is no way you can go wrong.