Simply put, this is a "love it or hate it" entry in the series, no middle ground whatsover.
First off, I loved this game, the battle system in it is enough to drag you in. Yes the linear progression and leveling up limits this game from greatness (it's like a railgun shooter in RPG form) but for me this couldn't have been better. I'm a gamer with unfortunately not enough of a time frame to grind an RPG like crazy these days, so the linearity was a blessing. The battle system is where it's at! Never before have I seen strategy and heart-pumping action blend so well. Think of it as Kingdom Hearts and Final Fantasy's ATB system combined. Very satisfying.
One thing that failed me in this game is the story, it never really grabbed me. The dialogue was interesting and sometimes funny with awesome voice overs and epic delivery but the plot itself felt lacking. I found the story kinda confusing with the Fal'Cie issues and the ending was very cliche. Not a shining point in the game aside from the gorgeous eye-candy.
Bottomline, you'll either love or hate this game, period. But what I can confidently say is that if you hated FFXII you will most likely find this game redeeming and rejoice while having alot of fun with it. Don't expect to have a ton of things to do after you finish the storyline though.