Crisis Core lived up to most expectations.
The story will be the first thing I talk about. It is amazing, to be blunt. Exactly what a game in the Final Fantasy series should be. Additives to the original story excited the player while never creating plot-holes to crawl through. Plus, the graphics in gameplay and the cutscenes are beautiful, some of the best I've seen on the PSP.
Secondly, the gameplay itself is something new. This time, the battles in the game are not turn-based, but real time, (to an extent). The battles involve running to the foe this time, and then using the right attacks judging its power and speed. It still has something from the original Final Fantasy VII, however. The use of materia is still present for the enactment of any actions save for the basic attack. Magic, summon, command, and support materia are all still here.
Finally, the side quests of this game - or the missions - are what make up most of the action in the game, truthfully. One can accept missions at any save-point to go on quests for various items and materia, battling all sorts of monsters and bosses. Doing so is great preparation for the assignments ahead in the story.
The game does have a slip, however. Simplicity. The battles can be incredibly easy and many can be won simply by button-mashing your attacks. Moreover, if one completes as many missions as possible after each chapter, as many people do, it more or less acts as powerhouse training, making it nearly impossible to lose.
Also, the game itself is relatively short. The missions make up most of the action, as I have stated, and even so, the game doesn't take more than 10-20 hours to beat. Nevertheless, the game is still incredible. Diehard Final Fantasy fans should surely go and pick this one up. Overall, it's quite worth it.