A shaky start, but ultimately a good game.
The story of Final Fantasy XIII has both the deep sea area, and the shallow beach. The world view, the concept, and the theme are all very ambitious but ultimately fall short in delivery because of its traditional structure of a weekly 16-page shounen manga text book style. The exposition, the gathering of companions, figuring out the common destiny, and ultimately overcome the destiny has all been used too frequently.
However, it is not to say that you can not deliver a good shounen manga story, and this is exactly what Final Fantasy XIII is -- a great shounen styled story.
The gameplay has not involved too much. The game uses ATB, or Active Time Battle system, where it is turn-based but the enemy will not wait for command inputs. So it can be understood as a semi-active turn-based gameplay.
While the AI is decent, and will get you through the game, it fall short to deliver a comprehensive AI system: Beside changing roles or jobs, on the fly which dictates your AI action, nothing else can be altered for you AI teammate. That's right; no turning off skills that you may not want your teammate to use, no manual quick targeting to ask your teammate to attack a certain enemy, and no prioritization of skills or spells.
The leveling system has also been cleverly disguised as a Crystarium system where you earn CP after battle and can be used to alter the character's stats. Your Crystarium level are 'capped' at each point of the story, so XIII provides more challenges than the previous Final Fantasies.
While the battle system is streamlined, and satisfying; the AI should of been more developed.
One of the most glaring omission and departure from the usual Final Fantasy is XIII's lack of town, and shops. The game flows from CG movies, to fighting enemies, to walking in a linear path, then more CG movies, then more fighting, then a boss: repeat. Although many long time fans may be disappointed by this fact, it is not all intolerable especially the combat and the CG movies decent enough of a distractor from these omitted elements.
The Sound and Music
XIII's music is great, it has a wide variety of genres: ballad, pop, techno, trance, classical. Most of the tracks are great -- although not too memorable. The Japanese voice actors are of the high quality Japanese anime caliber, delivering natural speech and great expression.
While the story takes somewhere between 40 and 60 hours to complete and another 20-30 hours of additional "hunt" missions to be done, players may not wish to replay the game again in its entirety simply because you probably only want to go through the same one-way path once.