About the only character we all care about:
Jigglypuff seems to be buffed in general. Rest kills at lower percentages than Brawl, but is still nowhere near its Melee strength. The hitbox seems bigger, though, so there might be quite a few ways of comboing into it. Her back-air has a ton of knockback, and seems like it would be her primary killing move. I haven't seen anyone use it to carry another character off-stage, and I don't know if it has a sourspot. Her fair might suffice, but not being able to carry would be a pretty big loss. Sing is still useless, Rollout is still useless, and the custom moves do little to help, it seems. Her up-tilt seems pretty fast, but I haven't seen any analysis of its hitbox yet. Other than that she seems largely unchanged, with minor buffs to damage for a lot of her aerials.
The Brawl engine really hurt Jigglypuff, and Smash 4 seems to have toned back some of the changes. Even just the increased hitstun can only be a good thing for the Puff, so I'm confident she won't be anywhere near as horrible as she was in Brawl. So good news, I'd say.
Also,
uair to Rest might be a thing again.