I didn't have a problem with Noel. He had an interesting back story and relation to the villain. Though I'm guessing he's blaming himself for what happened with Serah. And since everyone is living forever, he's had a lot of time to be depressed over the subject. The game is like 500 years or something after XIII-2.

Hopefully, they work in all of the gods they have in their mythology with their closure. It meant a lot to the world setting, so I'd hate to see it ignored for the conclusion.