The Ogre Battle 64 OST set up is almost exactly like the Tactics Ogre OST, with three CDs altogether. The first CD contains the music from the game, and the second and third are the midi-arranged versions of all the tracks, obviously sounding much better than the in-game music, whose sound loss was primarily due to the sound compression needed for a cartridge-based game. The quality is immediately apparent upon listening; most people will prefer to only listen to the second and the third CD, simply for the quality.
The first warning right off that I have to say is this: if you buy this expecting an entirely new soundtrack, you will be disappointed. Out of the 61 tracks for the game, only about 40 or so are actually new and composed solely for Ogre Battle 64. The other 20 or so tracks are reused from the previous two games in the Ogre Battle Saga series, Ogre Battle and Tactics Ogre. It's a great deal of new tracks, but the new tracks are spaced between the old in such a way that I was almost left with the impression that there were very few new tracks.
The second warning is that if you buy the soundtrack hoping for more of Iwata's or Sakimoto's music, you will be more than just disappointed - you'll probably be completely crushed. All of Sakimoto's tracks are completely recycled, and Iwata contributes very few new tracks (a majority of his are entirely recycled as well from both Ogre Battle and Tactics Ogre). It only makes sense, when one realizes that Sakimoto is busy composing the soundtrack to the upcoming game Vagrant Story and Iwata is working on other projects.
However, for the good news, most of the new tracks are composed by Hayato Matsuo, who many will recognize as being the third composer in the original Ogre Battle album. Very few of the reused tracks in the CD are by him (only one or two, I believe), and he contributes to the majority of the album in truth, which explains the strong Ogre Battle flavor that the Ogre Battle 64 soundtrack has. Very little in the music is reminiscent of Tactics Ogre other than the general excellence.
How does Hayato Matsuo stand up when compared to Sakimoto and Iwata? My opinion is that the Ogre Battle OSV didn't accurately showcase his talents enough when it comes to composition. Blending in easily with Iwata's and Sakimoto's orchestrally grand style, Matsuo creates unique compositions that still have me remembering them long after I've heard the songs. All his compositions, being mostly battle-based music, are intense and explosive, with heavy use of the percussion and horn so familiar from Ogre Battle. However, he has lightened both with the use of the strings to describe the melody (unlike his use of horn to convey the melody in Ogre Battle), and a very unique use of piano as part of the bass to bring up the high-powered intensity.
Fans of Sakimoto's music should definitely get a chance to try Matsuo; they both have the same amazing intensity to their music, though their means are slightly different. Sakimoto brings intensity to his music more through building up by adding instrument after instrument into a cohesive whole, while Matsuo is just insanely high-powered from beginning to end of the piece. However, the result is the same: breathless enjoyment. Fans who remember the intensity of the battle music from Ogre Battle should definitely enjoy his music in Ogre Battle 64. The "World" songs are particularly excellent in conveying Matsuo's ability to convey the sheer intensity and richness of the game world. In particular, "The Sensational World", "The World of Today", and "The World for the People" are absolutely astounding.
Matsuo does not contribute many of the slower pieces in the soundtrack; many of the recycled ones function for that purpose alone. Some of his slower tunes, though, do disappoint - "Funeral" is a fairly bland and pointless track, in my opinion. "Amazing Grace", however, is a lovely piece; the "vocals" carry the piece along into evoking a feeling of mystery, and his other "scene" pieces are quite elegant. He composes the final set of tunes at the end of the game, and they do not disappoint - "Alone" is a lovely composition and successfully evokes a wistful feeling. However, his real strength is the intensity of his battle music, and those are the truly memorable ones from his compositions.
As for the other set of new tracks, those composed by Iwata, they are a pleasant surprise, as few as they are. I was rather disappointed by his showing in Final Fantasy Tactics; his pieces were fairly bland and uninteresting in that soundtrack, but his new pieces are not that case in this game. Iwata's new tracks primarily focus on the miscellaneous tunes that are rather hard to classify--the "scene" pieces, perhaps. "The Fatty Rat" is a rather interesting piece, and "Deathagony" evokes the same feeling of eeriness that his earlier piece from Tactics Ogre, "Fog of Phantom", does. He composes nearly all the terminally short pieces (less than 30 seconds), the ones that cry to be expanded upon - "Graceful" being one in particular that comes to mind. Also, the recycled pieces of his are among the better pieces that he's done.
Finally, to speak of the recycled tracks of Iwata, Sakimoto, and Matsuo, they are, for the most part, simply rehashes from the older games. However, the bonus to this CD is Matsuo's arrangement of Sakimoto's "Revolted" from Ogre Battle; the music has evolved drastically from the original piece. Slowing down in tempo from the original, the first half of the piece is simply the same song as before, with its memorable "call and answer" through the strings and the horns, before then moving into a surprisingly sweet version of the same melody, with the use of a very beautiful clarinet solo. However, the real surprise is when Matsuo adds his touch right after, with his distinctive use of percussion and piano, using horns to carry the melody along into an extremely militaristic and triumphant ending. Simply beautiful.
Overall, the CD set is definitely worth getting, even if you do have the earlier Ogre Battle Saga CDs. The rehashes are annoying but don't detract from the soundtrack as a whole too much. It's definitely for the Ogre Battle Saga fan, and even for those unfamiliar to the series.