I will probably post a full review one of these days but just want to go on record as saying this soundtrack is WAY overrated. I truly hated it at first and though after several listens it's become more tolerable there's still no way in hindsight I'd spend my money on this thing.
Yes the soundtrack is virtually all live instrumentation (some full orchestral, some jazz, lots of ethnic music), but what good is live instrumentation if the compositions are generic and uninspired. I'll admit there are a few pretty decent chill-out tracks but you can probably pick from any dozens of proper world music albums and more than a few game soundtracks and get far better.
As usual you've also got the Sega OST syndrome of throwing every little meaningless diddy of a music track in there, completely oblivious to how it affects the flow of the soundtrack.
As a two-disc soundtrack it'd be much more tolerable and as a single disc best-of collection (without all the reprises of each theme, which don't really vary all that much) it would perhaps be satisfactory, but I couldn't recommend the overpriced three-disc set to anyone except those willing to filter a lot of filler for a few decent, mostly chill-out world music tracks.
No disrespect to those of you who are fans of the soundtrack (most of whom seem to have played the game, which I admittedly haven't) but anyone who has passed over Sega's far more imaginative but less hyped Nights ~Journey of Dreams~ for this is IMO making a huge mistake. For that matter Final Fantasy Crystal Chronicles ~The Crystal Bearers~, which I've just started listening to recently, follows much the same pattern of using varied musical styles, live instrumentation, and stage music mixed with cinematics, and does a far better job of it.