Vagrant Story has the most in-depth combat system of any RPG ever released on console. It has tons of replay value.
Of the many features employed to tell the story (including a rich musical score imbued with environmental noises), the one that strikes me most is the implementation of the age-old speech bubble. It's amazing what a simple pointer to a moving mouth does to a character's speech. The presence of the bubbles works so well that the lack of voice acting is hardly bothersome.
Speech bubbles would be nothing without the words to fill them, and the level of writing is flat out impressive. A medieval tongue is used gracefully without falling into the trap of becoming overplayed. The words simply embody and hold together the different elements of the game.
Despite not having the traditional auspices of an RPG, there's still a sense that Vagrant Story is turn based, as if a timing mechanism was happening underfoot. When Ashley makes an attack, a list of your opponent's body regions comes up. For example, if you choose to attack the legs, you'll eventually be able to limit your opponent's ability to move. Your initial attacks can then lead into combinations.
At the very core of the combination is the 'alert' system. An exclamation mark appears when your weapon strikes your opponent. At that precise moment, you hit a button, and then another, and another, and so on. It's like Squall's Gunblade attack from Final Fantasy 8.