>>32626784GB Sounds is fantastic in concept but it's really, really bad in execution. It's quite inaccurate, especially with regards to the Gameboy's waveform channel, which they just turned into a third pulse channel, ruining any song that used the waveform's unique sounds for its melody like the National Park theme.
When I first played HGSS I didn't notice anything wrong at all, but then I got into hacking, spent a LOT of time with Gen 2's audio capabilities, decided to replay HGSS (specifically the Drayano hack, which gives you the GB Sounds at the start of the game), turned it on, and was immediately horrified at what I was hearing. It was like going to Disney World and seeing Mickey Mouse take off his head revealing a man in a suit.
Again, it was fantastic in concept, just executed really bad. I imagine a GBA Sounds in ORAS would've worked a lot better because DirectSound is a lot closer to MIDI and the GBC channels don't play a very large role in most songs, but then ORAS half-assed a lot of things so they didn't bother putting a GBA Sounds in the game.
