The only characters in XIII that I really, REALLY liked were Light, Snow, Vanille, and Sazh. Everyone else really just didn't do it for me. Chapter 11 was my favorite chapter ever; I absolutely LOVE Gran Pulse, it's so amazing and beautiful...I wish I could live there for just a day. Now, if you don't run around doing all the missions/hunts in Chapter 11, it WILL be a little hard, but with a bit of grinding (I think I put over 20 hours into Ch11 -- I know it's quite a bit but I've seen save files that have over 999 hours put into the game), things become so easy.
I like XIII-2 more than XIII. I think the beginning of 2 faster paced and easier to get into, but 1's was just..bland? Kinda, and a bit too hard to get into. And something weird, I know the gameplay of both are pretty much the exact same, but 2's feels better in a way that I just can't explain.