I like it.
Awesome! There's someone else who actually like FFXIII other than me. Lots of people are screaming blasphemy that it's different from the other parts of the series. I personally love it.
Anyways, to the art. The chibi-Lightning looks great, especially her body! I love the way you did her hands and feet. It's really cute. Your attention to detail on her outfit is very good and she looks just like the in-game character.
The background looks too unrefined in comparison to the character, though, mostly because she is done with outlines and the rainbow isn't. If she's supposed to be walking on the rainbow, it would look better for the rainbow to be drawn using a similar medium (outlines/clean color) as the character. Your clouds are also really funny looking.
Good work on the character; the background needs work. I do like this piece a lot, though!