Please keep this thread spoiler free.
So I've been playing XIII-2 and it's interesting. I'm still trying to decide what my opinion of it is, so forgive me if I sound rambling. I'm not too far from the end of the game, with 80ish fragments out of 160. It has a lot I like, such as the excellent fast pace battle system, the expansive, beautiful world and a lot of non-linear and optional content to explore.
The plot is just ok. I don't think Square Enix quite understand time travel and paradoxes, but it's an interesting enough story. It certainly an improvement over XIII. It also has a lot of bizarre musical choices, with a lot of singing, including an insane rock version of the chocobo theme with lyrics.
My major issue with the game though is probably its origin. XIII-2 came about because they had a lot of art assets left over from XIII. The time travel crux of the story basically allows them to jump around to these assets with no context of how the areas connect. It also allows them to reuse the same area over and over with quick colour pallet changes. I've also heard things about the ending... but we won't talk about that here.
Overall it seems like they listened to some fan feedback (its certainly not as linear), but it really isn't the quality of game Final Fantasy used to be.
Also, the moogle in the game talks. And it's not the voice you wanted him to have.
Let's be honest; this is the voice we all wanted:
http://www.youtube.com/watch?v=QBG4TUPxQ0U