Alright, here's the report so far, using FF7MIDI to test out some midis I know well, using my WDM wunder-device...
Unlike what Goku7 thought, Drum compatibility is NOT broken, many drums sound well-improved, although they seem alot more military-like (gee, considering they came from FF7)
Guitar, on the other hand, is another story. Most of it sounds not-so-good, but then again I never liked the guitars on FF8 anyway, I think that's where the PC version improved (no offense Sam), except for one sample I can't put my finger on - you can even hear fingers stroking over the strings like it's a real person playing. Spooky.
Woodwinds, flutes, etc...they all sound great
EDIT: Ok, NOT kidding, One Winged Angel, I almost swear it barely choruses out "Se-ir-rouh". Wierd.
Chorus - Downright spooky. You should hear Seph's theme, give a new meaning to "-Evil-" So far, though, no bursting out "FIIIITHOS" when I least expect it
Trumpets and brass sound superb.
Synth pads and the like are also amazing
Various keyed instruments get interesting and varied results...Aeris' theme sounds like it's being played by Julia!
Stringed instruments are amusing to listen to just because I recognize them..Fiddle De Chocobo sounds like it's being played during the Garden Festival!
Bells are amazing to listen to...the Aeris Church Theme and the Song you hear when Bugenhagen tells you about the Lifestream are dead-incredible.
That's all I can pick out for now, but it mostly sounds amazing, except for those annoying guitars and the off off-whistle or key instrument.