XIII-2 improves so much of XIII's pitfalls, character interaction, the abilitiy to return to areas previous visited, so much has changed that really fixes everything
The storyline is good, it connects nicely to XIII without retconning the original story. The storyline ties itself nicely to the ability to go back and forth to areas at any moment.
The gameplay has changed a fair bit, you now have the abilitiy to jump whenever you like (which is honestly useless as 99% of jumpable areas are noted as being jumpable anyway).
The battle system is unchanged, however you can now switch party leader easily, personally I'd still like the abilitiy to manually control all my characters but eitherway this change is more than welcome.
The ability to capture monsters is huge, at first I expected this to be something quite novel, but its actually quite addictive, each monster has its own quircks and trying to find the items required for levelling up is quite difficult at higher levels.
The music in this game is honestly the worst thing, far too many vocal tracks, the chocobo theme is Metal.... the instrumental tracks are great and I even like some of the slower vocal tracks too, but I think the soundtrack was a little too experimental.
Box was great, the cards were as good as is to be expected, the artbook however is brilliant, I love the art to this game so being able to see the early concepts was a real treat. I'm still yet to listen to the soundtrack disc that came with the game so I can't make an opinion on this however.
Overall I'd say top stars, I love this game, I'm currently at the very end, going about collecting everything I can, leveling up all my characters, so many sidequests avaliable.