This RPG has a fascinating story, and has innovative battle mechanics for its time. Gamespot criminally underrated this.
The story starts out with a cliche damsel in distress rescue, but greater events and larger powers quickly start clashing and dragging the characters into a battle involving ancient powers threatening the world. There's plenty of twists in the story that keep things interesting and keep you guessing. I also enjoyed the character's personalities; they're well-developed and unique.
The battle system is what I find really fun about this game. Each character (minus Shana who sucks) have a set of "Additions" they learn that make their basic attacks more powerful, and generate SP once you acquire Dragoon forms. They require timing of button presses to moving squares on the screen. As you use them, their power increases, as well as the SP they generate. You gain new additions as you level, and they become increasingly more challenging and complex. Any addition with more than 2 parts can have a "counter" in the middle, where you have to press "O" with the correct timing, or you are knocked back and take damage. Another interesting part of the battle system is the Guard feature. You can guard your character to mitigate damage done, and it also makes you impervious to status effects. It also generates 1/10th of your HP
Each character has a Dragoon form that corresponds to their specific Dragoon spirit. They can use a charged physical attack or magic while in this form. In the beginning this is very useful, especially for bosses, but once you get better additions, the damage bonus from Dragoon form becomes rather obsolete.
Leveling is typical for an RPG, you gain experience from battles and level up. However, your Dragoon forms also have separate levels, and you learn more powerful magic as that level increases. Your Dragoon level increases with the SP you earn from completing your additions properly. This is an interesting approach, but there isn't a way to know your progress to the next Dragoon level, which I find somewhat frustrating.
The game's soundtrack is fairly well done, giving each area its own unique feel. There's also lots of animated noises of birds chirping, crashing waves, or wind blowing in the desert depending on where you are, which I enjoyed.
One of the biggest flaws the game has is its lack of replay value. I love the story and characters, but the only reason to replay it would be to use characters you never bothered with in order to experiment with their play style. There also aren't many sidequests to do, so don't expect to be able to run off and quest to get specific characters their best equipment. The best armor in the game has to be purchased, and it fairly expensive if you want to deck out all the characters you regularly use.
Sony did a really great job with this game, and it's something that no RPG fan should miss!