Final Fantasy: Crisis Core isn't a turn-based RPG as what most are used to. The battle system is a combination of hack ‘n’ slash with magic and luck-based summons. This does not make it less of a strategy game though. A well timed dodge and choice of magic can make the difference.
The CG cut scenes are stunning and so is the voice acting and soundtrack. There are many side missions to do at any time through the game and offers many hours of gameplay if you like to fully complete a game otherwise the main story may be a little too short.
If you are a Final Fantasy fan then I would recommend buying this just for the story. The gameplay is just a bonus.
Just a side-note. People may say that leveling up is random and it would seem that way however there is an experience system (you just don't see it). This isn't a big deal anyway as you will notice that you will level up often.