Having just finished the game a little while ago, it's not bad. Wasn't great. They hinted at a lot of back story that, had it been explored more in depth, would have been great. But instead of doing this (and making the world feel more alive), they flip-flopped between characters too much and didn't give them room to grow.
The battle system is pretty to look at, but was pretty much "mash the button" and just flip to different classes as needed (and hope it didn't decide to use the extra-long switch mode which might get you killed since you need to heal...).
The level system was horrible designed. Was all about trying to make it look pretty, but wasn't great. The whole fact that levelling up was capped the entire game was the worst design choice....
They had great story ideas with the purging of people but quickly dropped that idea to just focus on you being chased for becoming whatever-it-was called. When the people started to rebel, that was making it look up, but then they just... gave up? Stopped fighting? Was just gone (and now that I'm playing the sequel, it does make references that people lasted in that longer then the little battle you see).
Then could have helped build up with Sazh's son, what happened and how, and then the final ending... but he felt just thrown in too randomly that I didn't care really.
Snow wanting to be a "hero" just made him feel like a douchebag, and never did anything impressive. Just a loudmouth that talked himself up.
Serah, like Sazh's kid, felt wedged in.
Would have loved to see more about how the war 300 years in the past had effected the world instead making a odd garbage dumping area. Maybe have had it as a no-man's land/blackmarket city? Robot's that longed to go home? Anything more then being a mere foot note.
The major wasted effort was when you finally reached the town on the main world and it was empty. They have an amazing concept there, a town (that should have been larger) were everyone had been forced into a war they maybe didn't want, and lost causing them to become those monsters in it. Give the monsters some desire to want to be human agin, lingering memories, actions that would have given the players knowledge that these were the people whom lived there.
So much wasted potential...
*automatically refuses to place horse heads in anyone's bed*