Satoshi's maturity level in XY has also greatly improved a lot. He didn't start the season off making dumb mistakes like a brand-new trainer, and he's thinking and planning and such. I don't think it's quite as dark as BW (at least the parts of BW I saw, which was admittedly little), but I feel like Satoshi has improved enough to actually be a likeable character and a good trainer; if he's going to make Champion any generation, this would be it.
But it's also the other characters (Citron and Serena for sure; Eureka occasionally gets on my nerves, but she's much better than I thought she would be
) and the Pokémon themselves that really make things shine.
I guess it also helps that I really like all of the new Pokémon introduced this generation, so it's great to see them all on screen!
I won't give any spoilers, though; you'll have to watch and find out for yourself. :3