This addon... is really impressive.
It's a complete restoration of the original SRB2 OST and sounds EXACTLY like the original, except WAY higher quality. You can even hear things you've never heard or noticed in the original!
The fact that Goldyblox was able to get production MIDIs and patches from current and retired Sonic Team Jr. staff is also incredible.
Not every song is restored yet, but restoring the soundtrack is not easy, so give them time, the ones that aren't are ACZ1, ACZ2, ERZ1, BCZ1, BCZ2, and the credits (but it actually is just "Sonic & Knuckles" from the Virtual Sonic album, so it's not in need for restoration.)
Other than that, the only issues are really small, mod support depends, The 2.0 conversion pack actually doesn't work with this mod due to that mod using the original map-based names (example: O_MAP01M) while this mod uses the modern names (example: O_GFZ1)
That's not really an issue though, if you want, you could change the file names of this mod's music, though make a copy first and don"t release the modification. You can use the same modification in 2.1, but you'll have to convert the title screen to OGG Vorbis for 2.0 (since 2.1 supports FLAC, but 2.0 doesn't)
In the end, this addon is Outstanding!!!