While I agree SOME things improved on FFXII, XIII just did not have anywhere near the depth of XII's combat and customization system, nor did it have the really challenging encounters that even the main story could provide in that game. Actually, XII had very similar level design to XIII, except there was no transition to battle (you cannot tell me that wasn't a disappointment and a HUGE step back from XII to see enemies on the field and then transition to a battle screen) and the side paths were legitimately interesting to go down and had reasons for doing so. There was so much branching off of everything that if you actually explore (as I think the game designers intended you to) you could rack up a HUGE play time before you've even scratched the surface of the story.