By all estimation Final Fantasy XIII Original Soundtrack Plus should be an inferior album to the complete four-disc original soundtrack. It includes far less music in all, with the selections present consisting mostly of pre-final instrumentals or altered vocals, and only a couple truly new arrangements. Yet when it comes to the question of which album I'd rather spend my time and money on, Original Soundtrack Plus wins out.
The most significant portion of OST Plus is the "alpha" and "prototype" versions of orchestral tracks from the original soundtrack. In general these lose the live orchestral elements from the final versions in favor of the sequenced orchestra used during production, but the sound quality is robust enough that they hold up well. The standout battle theme "Boss Battle Alpha" doesn't have quite as much oomph in the bass spectrum as its final OST version "Saber's Edge", and the piano is mixed less prominently, but a casual fan not listening to the two back to back might be hard-pressed to tell. The backing instrumentation in "Shugeki" (a.k.a. "Fang's Theme") has a fuller sound in OST Plus, but its lead instruments don't have quite as much punch as in the original soundtrack. "Last Battle Prototype" is a scaled-down version of "Nascent Requiem", lacking the excellent opening and transitional segments from the final version as well as some additional instrumentation. The longer, more ambitious original version is far more impressive artistically, though taken purely as an action theme the OST Plus version is effective enough.
Though not orchestral, another standout track from the original soundtrack that made the cut in OST Plus is "Can't Get a Break", retitled here as "Sazh Prototype". Compared to the OST version I actually prefer the less forceful piano in OST Plus, not to mention the saucy jazz flute that occasionally surfaces.
Five of the tracks in OST Plus have had vocals altered from the original soundtrack or removed altogether. The OST Plus version of "Fighting Fate" keeps the low, ominous brass orchestrations of the original while losing its grating chorus. "Cocoon de Chocobo" swaps the original auto-tuned Japanese vocals with the English ones from the U.S. release of the game, "The Sunleth Waterscape (International Version)" contains slightly less sappy vocals than the original, and the second version that concludes the album drops them altogether. Unfortunately fundamental problems in all three of those latter tracks make the minor vocal modifications moot.
In the original soundtrack "The Gapra Whitewood" did all the things right that "The Sunleth Waterscape" did wrong, with naturalistic synth, far more interesting percussion and more subdued vocals, and the version in OST Plus does those things even better. Whether due to the removal of most of the vocals or some tweaks to the instrumentation, the earthy, uplifting tones of the piece are even more pleasing here, making this perhaps my favorite track from either of the Final Fantasy XIII original soundtracks.
Accompanying the numerous alternate versions are a couple tracks with new material. The biggest surprise of the album is "Hope PfNer3". Among several uninteresting character themes in FFXIII Original Soundtrack, Hope's was one of the worst, its tedious simplicity made more apparent by some plodding arrangements. The more elaborate piano arrangement in OST Plus makes a huge difference; with a new sense of dignity and grace the theme for the first time makes a desirable addition to the FFXIII soundscape. "Defiers of Fate" also has new meaning in its OST Plus rendition. Though neither the sub-par hard electronica intro nor the generic main theme is improved in OST Plus's "Palamecia Assault Version", a newly added climax takes that early synth and juices the frequency up into a hyperkinetic sci-fi finale, bringing at least a momentary sense of satisfaction.
With over 20 minutes of space still available on disc, it's a shame Square didn't take advantage of Final Fantasy XIII Original Soundtrack Plus's potential as a pseudo best album and include prototype versions for a few more of the OST's standout themes. Were that the case it'd make a solid collection of music, even lacking the full live instrumentation of the orchestral pieces. As it is, anyone wanting to own FFXIII's music on album is faced with the difficult choice between a four-disc set with maybe a disc's worth of noteworthy material and this less complete but more easily digestible single-disc collection. Neither solution being ideal my own recommendation would be to download each album's best tracks individually. Still, for those who just want to keep up to speed on the series, and who don't mind missing a few highlights and quite a few lowlights from the full soundtrack, Final Fantasy XIII Original Soundtrack Plus is a respectable choice.