One of the best battle systems I've enjoyed in the FF series. Building schemata and taking down enemies as an 'Army of One' with Lightning is just so satisfying.

Has my favourite gameplay in a Final Fantasy game outside Stranger of Paradise which is something else entirely, unlike any other FF game. The music in Lightning Returns, likes its two predecessors, is also great. Whereas the art direction is largely uninspired, with a few standout areas; owing, I imagine, to the smaller budget, and recycled assets.
I very much liked the sombre atmosphere. The people have accepted that their world is dying. Their fated demise lingers in the horizon, drawing closer each day, and when death reaches them it will be met with apathy. It reminded me of the books Ice by Anna Kavan, and The Last Man by Mary Shelley. It feels disconnected from the events of XIII-2, however. In a vacuum the plot is fine; as a sequel it's a poor conclusion.
I mainly care about the gameplay. I loved it so much that I immediately beat LR again after completing it the first time. There are enough classes, weapons, customisation, etc. to keep you experimenting, adjusting things as you arrive at a new boss (particularly on NG+). I wish they'd make another game like this.