I guess the characters are a love or hate thing. The character development was my favorite thing about the game. Even Hope! The difficulty is in my opinion, almost perfect. You'll find that the game heavily discourages you from powerleveling. You don't need to and really you can't except for one area towards the end of the game. Boss encounters will keep you on your toes. When you get stuck, instead of power leveling like most people tend to do in other entries in the series, you come up with a new strategy, adjust your Paradigms as necessary, and try it again. Buffs, debuffs, and status effects are useful. There are some fights where you need to bide your time, making your party stronger and weakening the enemy, and there are some where you'll need to be quick and shift your Paradigms every few seconds. One nice thing about FFXIII is that it removes the tediousness a lot of RPGs have.

(Paradigms, if you didn't know, are job sets. You have a deck of six Paradigms. In each Paradigm you assign each of your party members a role. So you'll have a Paradigm where say, Lightning is a healer, Snow is a defender, and Sazh is casting buffs on your party, and when you're good and ready switch to one mid-battle where all three party members are in attacking roles.)