Dont really think it looks very good.
To begin, with reference to the OP, the darkest FF is without a doubt FF12. The reasons being the metaphorical allusion to the events of Hiroshima and Nagasaki, not to mention the soundtrack.
Main character Noctis... looks the same thing as Squall, Lightning was the same thing as a female version of Squall and then they changed Cloud's personality in Advent Children so he was another Squall persona.
I'm getting very fed up with Squall carbon copies, would rather see more charaismatic, less-emoish main characters. His hairstyle looks awful as well. Looks like Noctis and Stella will be the same thing as Squall and Rinoa. Seems like it will be bland Twlightish romance to me.
Gameplay, of what I've seen the gameplay looks good.
I think it will be similar to FF13, maybe 3 -5 hours of cutscenes, with characters talking incessently or giving monologues incessently, or arguing with each other incessently. Can't really say I'm interested in this title unless Square Enix show more footage that it will not be any of those things.
