Big let down from it's final fantasy predecessors. Not exactly sure what SE had in mind by going completely linear, but it completely ruins the feel and magic that previous final fantasy titles had.
I'm a big fan of the series, having played FFIII, VII, VIII, IX, X, X-2 (horrible), XI (still play on occasion), XII, and now XIII. XIII is by far the worst of the entire group. It's hard to understand how a franchise can make such a drastic turn for the worst, but SE has succeeded in doing just that.
Long story shore, if you're looking for a worthwhile RPG, this isn't it. I'm not even sure you can consider this game a true to form RPG....more along the lines of an action adventure game.
Those looking for a worthwhile RPG experience should try out Valkryie Chronicles or Dragon Age Origins.