I just completed this game. It is definitely not a regular Final Fantasy game. I'd say it's pretty good - the combat is fun (once you get used to it) and the game looks and sounds amazing. The story is confusing and unclear at times and the linearity is sort of a put off for me. I was also extremely dissapointed with the character development system. I had heard that it was a more developed Sphere grid system from FFX which I loved, but i turned out to be extremely limiting. It felt like a dumbed down version of that system.
Good: Presentation, combat, characters (minus Vanille), interesting story
Bad: Extremely slow start, no sense of freedom (until late in the game, even then it's limited), not many side quests, character development system