The only thing I really truly enjoyed about X was the CTB battle system. It was new, fresh, and it was to play around with.

That said...
The Sphere Grid system is my biggest gripe and makes me cringe. It gives you the false impression that you have the ability to develop your characters with a hands-on approach. It does not do that. You are basically railroaded in to one line of growth for each character with only minor pit-stops along the way. You can't open the sphere grid to really do anything you want until you're almost done with the game. And then what's the point? Everyone is pretty much already set in their ways and it's no use to change it.

The characters were meh. Archetypes that aren't even new for the series. I had trouble caring about any of them.

Much like XIII, this game is extremely linear and does not leave much for a second playthrough.